Depending on who you want to use, Dan Haren was either a 1.8 win pitcher last year, or a -0.6 win pitcher. The difference stems from Fangraphs using a pitcher's expected, fielding independent ERA (FIP), while Baseball Reference uses their actual ERA. Either way, if you're trading for Dan Haren and paying him $15.5 million, you're not using 2012 as your point of reference. Coming into the season, Haren had been about as consistent as a pitcher can be, posting four win seasons since 2005, including three seasons of six plus wins above replacement in the four seasons from 2008 - 2011. Injuries derailed his season, but given that he's effectively on a one year deal, he's an intriguing option.
Looking to the recently completed Ervin Santana trade, the Angels may not be looking for much in return for Haren. Sisk, the relief pitcher acquired in the Santana deal, tops out as a lefty one out guy, and even as such, may not even sniff the majors. They'd likely want more for Haren, but the Red Sox happen to have an abundance of what the Angels need - relief arms. After a core of Frieri, Downs, Walden, and Jepsen, the Angels relievers were pretty rough, leading to a team reliever ERA of 3.97, good for 12th in the American League. Although the Red Sox were 11th in the league, they do have spectacular relief depth. Alfredo Aceves could be a good match - he obviously needs a change of scenery following the repeated issues in Boston last year, and the Angels could use him as a swingman. With an exodus of starting pitchers, including potentially losing Zach Grienke as a free agent, and a reliance on young arms, the Angels could be very thin in their rotation, so Aceves could slot in there. Alternatively, if their pitchers resign and stay healthy, Aceves could be a multi-inning reliever from their bullpen. Despite Aceves having a projected salary of $2.6 million after arbitration, the Angels would actually save money by trading away Haren, since he has a $3.5 million buyout on his option year. The Angels may not want Aceves, given his discipline issues in both Boston and New York, but even still the Red Sox have a plethora of arms that are fairly fungible, such as Rich Hill, Scott Atchison (who would be under team control for another four years), or Theo Epstein's "replacement", Scott Carpenter.