Despite the massive spike in strikeouts (up from 20% last year), there really is an awful lot to love about Rasmus this year. His jump in strikeouts has also been accompanied by an increase in walks, from 6.9% of his PA to 11.5%, allowing for a respectable OBP of .349, despite an average of only .264. Perhaps most importantly, Rasmus seems to be trading strikeouts for some very impressive power (.230 isolated power, which is slugging percentage minus batting average, and a .495 slugging percentage), especially for an up the middle player. Out of all full time center fielders, only Vernon Wells has a higher isolated power and no other full time center fielder had a higher OPS. To top it all off, Rasmus has played slightly above average fielder according to both the ultimate zone rating (UZR) as well as John Dewan's plus/minus system.
Personally, I think LaRussa is nuts for antagonizing the third best hitter on his team, especially considering that the Cardinals have an emerging star who is putting up these impressive numbers at 24 and would be under team control for another 4 seasons. But, Tony LaRussa works in strange ways. You can't argue with his track record, but I still think he's kind of nuts. This is a man who wears sunglasses during all games so his eyes don't give away anything about the signals he's giving baserunners.
Again, this is a completely unfounded rumor, but you have to wonder if the Red Sox and Cardinals would consider swapping "problem" outfielders, sending Ellsbury to St. Louis in exchange for Rasmus. The Sox front office has shown they have no problem with strikeouts if you're producing runs, and LaRussa has always valued, perhaps over valued, speed guys. The big impediment to any deal might be service time and age. Ellsbury, though hardly old, turns 27 on September 11 and is three full years older than Rasmus. As such, he doesn't really have a ton of growth left in his game - I doubt he's to be able to markedly improve on his 2009 numbers, particularly in the power department.
Rasmus, on the other hand, is only 23 and has tantalizing power for a center fielder. If he can learn to get the strikeouts down to similar numbers to his rookie season without giving up the power stroke he could be a superstar. Of course, he may need to cut down on his strikeouts in order to maintain some of his gains this year - Rasmus' overall numbers are buoyed by a .331 average on balls in play. Based on some off the cuff estimates and some guesses (25% K rate, 10% BB rate, similar 2B, HR, 3B/PA rates as this season) I ended up with a .261/.335/.474 projection. While an .800 OPS is very good for a center fielder, it falls well short of superstar level.
The other complicating factor is money. Next season, I believe that Rasmus will still be a prearbitration player, making only about $400,000 (poor guy), while Ellsbury will be arbitration eligible for the first time. Ellsbury's "lost" season will certainly depress his value, but with all the negatives stacked towards Ellsbury (age, cost, length of team control, injury history) in the end the Red Sox and Cardinals might not match up. If you're Theo Epstein I think you have to give the Cardinals GM a call about Rasmus in the offseason.