Looking Ahead: Losses

After winning the championship, the Red Sox have a lot of players coming off the books. These include core contributors, including the entire swath of up the middle hitters, and guys you may have forgotten will be getting a ring for 2013.

Oh yeah, you were on the team (2013 salary)
Joel Hanrahan ($7.04)

Just as with Bailey,  Hanrahan came over in a trade with the Pirates, in one of the larger moves of the offseason (or so we thought at the time). Unfortunately, Hanrahan was bad, then injured. He pitched a mere seven innings ($1 million/inning!), before undergoing Tommy John Surgery. Given that he's a Proven Closer^TM, someone will probably take a flier on him on a one year deal with a team option, but we're probably looking at a return around the All Star Break next season. He won't be a great loss, doubly so given the emergence of Uehara as a closer and Uehara's affordable $4.25 million option, which vested in September, but the $7 million is always nice to have.

Rebooting the blog to bask in the brilliance of a championship

It's been an awfully long time, but I wanted to try and start writing again, in part to enjoy the current success of the Red Sox, and in part to get in the practice of writing a lot, to help with my dissertation.

I'll be looking at free agent losses, the roster as it stands for 2014, upcoming prospects, and free agents in the next week or two.

An Extremely Unusual Start

On Friday night, Alex Cobb had one of the most unusual lines you'll ever see from a starting pitcher.

4 2/3 IP, 13 K, 2 BB, 5 H, 2 ER

So, Cobb got a total of 14 outs. Twelve were via the strikeout (one of the strikeouts reached first on a wild pitch). Two of the hits were home runs. That means that Cobb only had five balls in play. Of those five balls in play, two were infield singles and two were ground outs.

Looking at the underlying numbers, Cobb was just as dominant. Of Cobb's 117 pitches, 77 were strikes, for an about average total. However, aside from the two home runs, the Padres were clear completely lost at the plate. They swung at 57 pitches and swung and missed at 22 of them (38%). For comparison, 10% is a good swinging strike rate, and Yu Darvish has the highest swinging strike rate on the season (16.7%).

To top it all off, Cobb managed to strike out four batters in the third inning. Despite that, he allowed a run, as Will Venable reached on a wild pitch strike out, stole second, stole third, and then scored on a balk. Cobb then struck out Yonder Alonso to end the inning. It was only the 30th time than an AL pitcher has struck out four players in an inning and the 60th overall. Striking out four batters in an inning is one of the rarest occurrences in baseball, just behind a perfect game and the unassisted triple play.

All told, this might have been the most dominant start when a starter didn't even manage to qualify for a win.

On swinging strikes, swings in the zone (or lack thereof), and strike outs

Following up on the comment on my Clay Buchholz piece, I wanted to examine how the swing percentage on pitches in the strike zone impacted strikeout rate. Thanks to Fangraphs excellent and customizable leader boards, I was able to get data for pitchers from 2006 to 2012 who threw for 100 or more innings. I did not want to go much farther back, as strikeout rates have changed considerably over the last few years, but also, swinging strike percent and swing rate on pitches in the zone are not available prior to 2005.

What are the Data I'm Using?
So, given 100 IP in a single season from 2006 to 2012, I had 986 total records from 306 different pitchers to go with. For simplicity's sake, I'm going to treat each season as independent, even though we might expect different seasons from the same pitcher to be related.

Creating the Basic Model
I used these 986 data points to create a linear model predicting strike out rate in K/9 IP using the swinging strike percentage. I originally considered adding the season to the model, as strikeout rates have steadily risen over the time period I'm looking at. While season was a significant predictor of K/9 IP when it was included in the model (more recent = more strikeouts), it didn't add much to the overall fit and only had a very minor impact on the model overall. In ecology, we often describe this as statistically significant, but not biologically significant. It often happens when you have a large sample size. Also, in general, I strongly prefer the simplest model possible, especially when adding variables marginally improves the fit. Guess I'm just a big fan of Occam's Razor. Without further ado, the relationship between swinging strike rate and strikeout rate is:
K/9 = 71.8*(Swinging Strike %) + 0.7892

The R² for this model was 0.6693, meaning that swinging strike rate explains 67% of the variability in K/9. That is a huge proportion, but it does leave room for improvement.

Examining the Residuals
A residual is the difference between the expected value from the model and the actual model. A positive residual means that the pitcher had more strike outs than our swinging strike model thought they should, while a negative residual means the opposite. In general, a lower residual means a better fit for the model, but you can also look at the residuals to see if there is anything consistent about them. In our case, we’ll look at the percent of swings on pitches in the zone. To do this, I ran another linear regression, trying to predict the residuals using the zone swing percent. This showed a significant trend, but with a much lower predictive value than the swinging strike rate (R²=0.136). When your residuals have a trend, it means that your model isn’t capturing something, but for our purposes, it is a good thing. It means that when pitchers have a lower rate of swings against pitches in the zone, they have a higher strikeout rate.

The Low Swing Pitchers
Over the entire data set, the average swing rate at pitches in the zone was 65%. Unlike some other stats, there isn’t as much variability in swing rates at pitches in the zone. The lowest average belongs to Doug Fister (55.5%, over the course of three seasons), while the highest belongs to Scott Baker (72%, over two seasons). Another way to look at the data is to examine whether or not the pitchers with the low swing rates on pitches in the zone have a high residual. In short, the answer is yes. Four pitchers averaged a zone swinging rate of 60% or lower, and had multiple seasons on record. Here are their numbers – remember, a positive residual means that a pitcher was striking out more batters than the model predicted.

Name	Seasons	Residual (K/9)	Zone Swing %
Doug Fister	3	0.873	55.5%
C.J. Wilson	3	1.678	57.5%
Jake Arrieta	3	0.992	59.2%
Mike Mussina	3	1.476	59.4%

So, we see a consistent pattern at the extreme ends. But, does swing rate on pitches in the strike zone explain most of the variability in K/9?

The Biggest Departures from the Model
To examine this, I looked at the pitchers who had: 1. The highest residuals, and 2. At least three years of data. If the biggest departures from our expected results (largest residuals), all have a lower than average swing rate on pitches within the zone, that would provide even stronger support that swing rate within the strike zone controls how . Of the 15 pitchers with the highest average residuals, only two have swing rates below 60% (Mussina and Wilson), while an additional six have zone swing rates slightly below average (60-64%), and five have zone swing rates that are about average (64%-66%). None of the pitchers with consistently high residuals have above average zone swing rates. Interestingly, many of the high residual pitchers who had  average to slightly below average zone swing rates also walked a lot of batters. If you increase the number of walks you hand out, you'll also increase the number of batters you face, which in turn should lead to a higher K/9. For example, think about two different pitchers. Pitcher A strikes out 25% of the batters he faces and walks 10% (Yovanni Gallardo) and pitcher B strikes out 25% of the batters he faces and walks 6%. Pitcher B is clearly the superior pitcher, but pitcher A will likely have a higher K/9.

Name	Seasons	Residual (K/9)	Zone Swing %
Yovani Gallardo	4	2.065	62.0%
C.J. Wilson	3	1.678	57.5%
Erik Bedard	3	1.623	64.2%
Mike Mussina	3	1.476	59.4%
David Price	4	1.343	64.8%
Ubaldo Jimenez	4	1.272	63.7%
Tim Lincecum	5	1.258	63.4%
Zack Greinke	5	1.179	64.7%
Jonathan Sanchez	4	1.176	62.3%
Clayton Kershaw	5	1.169	63.4%
Oliver Perez	3	1.154	64.7%
Tommy Hanson	3	1.148	63.0%
Josh Beckett	6	1.134	64.9%
Daniel Cabrera	3	1.119	64.8%
Jon Lester	4	1.112	65.7%

So What Does This All Mean?
I think there are several conclusions we can draw here. First, a lower swing rate at pitches in the strike zone does consistently lead to a higher K/9. Second, if a pitcher has a high swing rate at pitches in the zone, they probably won't outperform their predicted K/9 based on swinging strike rate. This makes sense; lots of swings will lead to more balls in play, which in turn will lead to fewer strikeouts. Third, there are other factors that aren't captured by just looking at swinging strike rate and zone swing rate. Most of the pitchers with the highest residuals in the model did not have extremely low zone swing rates. This may be attributable to "stuff" in general, so perhaps delving into PitchFX data would lead to a clearer picture there.

What has improved with Clay Buchholz?

Clay Buchholz has been the Red Sox best pitcher, and even edges out Dustin Pedroia as the Red Sox best player overall. He currently has a spectacular 1.19 ERA, and even more surprisingly, is striking out more than a batter per inning. While the ERA obviously won’t stay below 1.50, I thought it was worth a closer look to try and figure out where his strikeouts are coming from.

What Hasn’t Changed?
Before we get into the details too much, it is important to round up the usual suspects. Buchholz is not throwing a new pitch; he is still using the fastball, cutter, change up, and curveball that he has since introducing the cutter in 2011. Nor has he changed his approach. Buchholz still throws his four seam fastball about half the time and his cutter about 20% of the time, followed by his curveball and changeup with about equal frequency. Since Buchholz was hampered by injuries to start 2012, you might expect an increase in velocity, now that he is healthy, but we also don’t see a surge in velocity for Buchholz. In fact, Buchholz’s fastball is about one mile per hour slower than 2012. Buchholz’s control isn’t better either – he is still walking about the same number of batters (3.11/9 IP) and he is throwing the same number of first pitch strikes, too. Finally, and most perplexingly, we don’t see a change in his swinging strike rate.

Swinging Strikes and Strikeouts 
The big surge in strikeouts without an increase in swinging strikes is very odd. Swinging strikes and strikeout rates are tightly linked (R2 = 0.65 in 2012 for qualified pitchers), and swinging strike rate usually stabilizes before strikeout rate. Without an increase in swinging strikes, we should probably expect to see a big drop in Buchholz’s strikeout rate over the rest of the season. Needless to say, that would mean that he wouldn’t be the ace we’ve seen in the first month. Based on a linear regression from last season’s stats (it is still a bit early to be using 2013 stats), we should expect Buchholz to have a K/9 of 6.67, instead of 9.32. That strikeout rate would mean his expected ERA (xFIP) would be about 4.00 – hardly an ace, and maybe not even a #2.

A Silver Lining
There is one metric that Buchholz has improved significantly in – batters are swinging much less often at pitches in the zone this year (58%, compared to 65% in 2012). Currently, a 58% swing rate at pitches in the zone is the 10th best in the majors, and would have led the league last year. If batters aren’t swinging at pitches in the zone, that could mean two different things: 1. Batters are getting fooled by Buchholz’s pitchers, or 2. Buchholz is working the corners effectively, so although the pitches are in the zone, they are not good ones to hit. Looking at Buchholz’s heat maps showing where he is throwing pitches, nothing immediately jumps out at me to indicate that Buchholz is working corners better than previous years, however it is rather hard to compare the 2013 season to previous years because of the big difference in number of pitches thrown.

Trickier Pitches? 
If Buchholz is fooling batters, we might be able to see some improvement in the movement of his pitches. Thanks to PitchFX data, we have an amazing treasure trove of data. There is not a significant change in the amount of movement for Buchholz’s changeup or curveball, but he has added an inch of movement on his fastball and cutter (this combines both horizontal and vertical movement). Most of the movement for the cutter has been horizontal movement, which is not surprising as cutters often have more run when thrown slightly slower, and Buchholz is throwing his cutter two and a half miles per hour slower than last year. However, of the two pitches, only the four seam fastball has shown improvement. A big part of that improvement has been in the swing rate within the zone, as hitters have offered at fastballs in the zone 7% less often in 2013. The biggest improvement in that category is with the curveball; hitters have gone from swinging at curveballs in the zone 42% of the time, to an incredibly low 22% of the time. Although the overall movement of the curveball hasn’t changed, how it is moving has. Over his career, Buchholz has gone from having a fairly traditional 12-6 curveball (one that drops pretty much straight down, from 12 o’clock to 6 o’clock, if you were looking at a clock face) to one that has a lot more horizontal movement; at this point, he’s almost throwing a slurve (combination of a slider and a curveball), with over 10” of horizontal movement. Traditionally, most scouts prefer a 12-6 curveball, and a slurve often has a bad reputation, however, this pitch is working for Buchholz.

Looking Ahead 
Whether or not the slurve remains effective, particularly in getting called strikes, will be key for Buchholz’s continued success. I think a lot of that will depend on whether or not hitters adjust to the new, more horizontal movement of the pitch. If he can continue to fool hitters, he may be able to maintain an elevated strikeout rate, without having a typically high swinging strike rate. A regression to model strikeout rate using swinging strikeout rate and zone swing percentage indicated that a lower swing rate at pitches in the zone leads to a higher strikeout rate overall, and greatly improves the fit of the model (R2 = 0.83, compared to 0.65 with just swinging strike rate). According to that model, Buchholz’s K/9 IP would be about 7.50, leading to a much more palatable predicted ERA of about 3.50. Now that looks more like a #2 starter.

Koji Uehara in a Nutshell

This week was fairly representative of Uehara on the whole. He appeared in 4 games, throwing 4 innings. He showed excellent control, walking no one in those four innings, while striking out four batters. Unfortunately, Uehara gave up a couple of home runs - a shot to Billy Butler that tied the game in the 8th and a home run to Chris Young that cut the Sox lead against Oakland to one.

That is pretty much what you can expect from Uehara. Lots and lots of strikeouts (10.13/9 in 2013, 10.75 in 2012), almost no walks (a microscopic 0.84/9 in 2013, 0.75/9 in 2012), and lots of fly balls (59% in 2013, 51% in 2012). Sometimes, those fly balls are going to leave the yard, often times in bunches. Thankfully, they'll usually be solo home runs. The home run Uehara gave up to Butler was a crusher, leading to a Sox loss in extra innings, but on the whole Uehara is going to be an excellent contributor to the bullpen. The one thing we can't count on, though, is health. Uehara only threw 36 innings last year, and typically needs to have a day off between appearances. But while he is healthy, the Sox should enjoy the ride.

Breaking Down Webster's Debut

Thanks to the double header and the Lackey injury, the Red Sox called on Allen Webster. Webster was one of the two main prospects in the Adrian Gonzalez deal, and wasn't expected to pitch at the major league level outside of a September call up.


Good : The control. Coming in to this season, Webster had issues with walking too many batters (4.2/9 IP in AAA last year). The Red Sox believed this was in part due to where he pitched on the rubber, and shifted him to always throwing from the extreme first base side. So far, that appears to have worked. Webster walked three in 10 innings in AAA, and only walked one in five innings against the Royals, continuing his improved control from spring training (1 BB in 11 IP). At one point David Ross stuck out his right leg as Webster was getting set to pitch. The Royals announcers thought that it was a trick to confuse the batter, indicating that the pitch was coming inside when it really was going outside, but I'm not so sure. Perhaps Ross was simply reminding Webster to stick with his spot on the rubber. The release points from PitchFX indicate that he did a very good job having a consistent release point, both horizontally and vertically.

Bad: The command.The difference between command and control is a bit tricky, but to sum it up as briefly as possible, good control means you're not walking guys, good command means that you're putting the ball where you want it to go. Webster left several pitches either in the middle of the plate or waist high that led to two home runs and a double. He also got away with several other pitches. Thanks to his stuff, he may be able to get away with the occasional fat pitch, but major league hitters can handle a waist high fastball on the outer half, even if it is going 97. Webster only allowed two home runs in 130 innings in AAA last year, but allowed the same number in one start.

Good: The stuff. Webster had all three pitches working for him at points during the game. His sinking fastball was sitting mid-90s, and touched 97. He got several swings and misses from his strongly breaking slider and got at least one batter looking on a nasty front door change up. All told, Webster had five Ks to only one walk, had 14 swinging strikes (17%, an elite number, albeit in a single game), and on top of that he was generating lots of ground balls (7 GB outs to 5 FB outs).

Bad: The stamina. This is a bit of a nitpicky criticism, but Webster clearly is not quite ready to be a major league starter and take the ball every five days. The Red Sox were understandably cautious with him in this game, only allowing him to throw 84 pitches, but Webster was appearing to tire towards the end of his start. Although his fastball velocity did not drop significantly in the later innings, he didn't seem able to reach back to get to 96 or above in the fifth and sixth innings. Part of this is likely due to it being early in the season, as the Red Sox have taken to slowly building up minor leaguers arm strength, but Webster has had issues with stamina and efficiency in the past. In 2012 he only averaged 4.5 innings per appearance (24 starts, plus three relief appearances), but even if you toss out the three relief appearances that average is still only 5.4 innings per appearance. This is something that will hopefully improve over time.

All told, it was a great debut for Webster, and one that was probably five months earlier than the most optimistic projections indicated. It is still early, but so far the returns from the Adrian Gonzalez deal look promising. It wouldn't be shocking to see Webster be a contributor down the stretch, especially given the lack of other options should an injury befall a Red Sox starter.