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what's gotten into jake westbrook?

Pitch f/x charts for Jake Westbrook; 4.1.2012-6.19.2012 is on the left, 4.1.2011-6.19.2012 is on the right.
Pitch f/x charts for Jake Westbrook; 4.1.2012-6.19.2012 is on the left, 4.1.2011-6.19.2012 is on the right.

in case you're wondering, danup and i are going to swap days for the foreseeable future. do not adjust your set. it is not the weekend yet.

coming off a spectacular complete game by jake westbrook, i thought it was worth taking a look at jake and what he's doing this season. he looks a lot better than he has the past few years, and his results generally show it, despite his typical hiccups. as a high-groundball pitcher who doesn't walk or strike out a lot of guys, little tweaks in either direction make a big difference.

and you've seen those tweaks this year. modest improvements in westbrook's K rate and walk rate have transformed him from a 1 WAR pitcher to what looks like a 2-3 WAR pitcher. last year, he struck out 12.9% of the batters he faced; this year, he's striking out 16% of them. last year, he walked 9.0% of the batters he faced; this year, he's walking 6.5%.

what, if anything, is he doing different? his pitch selection hasn't changed much; if anything, he's relying on his sinker more - 65.5% in 2012 v. 63.6% in 2011. his sinker velocity has improved a tick (90.5 this year v. 90.0 last).

what's most striking, however, is in the graphs above.* westbrook is exhibiting more control over his pitches, his sinker in particular. just looking at the graph, the left side (representing 2012 pitches) shows his sinkers in a tight, almost perfect circle. this means that his sinkers in 2012 tend to move in a very regular fashion, both horizontally and vertically.

* you probably want to click the graphs to open them in a new tab. sorry about the sizing; internet explorer continues to hate whatever javascript SBNation uses in its software.

on the right (representing 2011 pitches),** his sinker spreads out in a blob rather than a circle, indicating that westbrook's sinker was moving unpredictably, particularly horizontally last year.

** i limited the 2011 graph to the same dates in 2011 as in 2012. when i first compared his 2012 charts to his 2011 charts, i thought the blobbier results in 2011 might be a feature of having more pitches in the mix. the discrepancy remained even after i switched to the april through june 2011 data. i also figured that using the same time period would eliminate the risk of including diminished control from periods late in the 2011 season, when westbrook had a lot of miles on his arm.

obviously, when westbrook knows how much his pitches are going to move horizontally, he can pick at the corners of the strike zone better, walking fewer guys and striking out more. you can see similarly improved control over his changeup as well.

what's causing his improved control? it's not totally clear. he may be continuing to see improvements as his surgery gets more distant. improved anatomical stability in his elbow would certainly help his control. he could have been working on his mechanics. it may be that some of the lost weight has helped smooth out his delivery. whatever the cause, i am tentatively optimistic that his improvements may stick.

we continue to get good news on the stragglers on the disabled list. jon jay has had great success in his rehab assignment at AAA. matt carpenter has also done well and may rejoin the team on friday. jay should not be far behind. this probably means that adron chambers and matt adams will rejoin the cast down in memphis.

chris carpenter has been making very optimistic noises about his shoulder strength. i'll feel a little more sure when he's on a rehab assignment, but at this point even vague assurances of his health appeal to me.

the timing of these players' rehab assignments are particularly important, given the upcoming trade deadline. the cardinals are 3.5 games out of the lead in the NL Central, and the division is very winnable. if chris carpenter is not coming back soon, the cardinals may want to pony up for one of the nicer talents on the trade market. if jon jay has a setback (or maybe even if he doesn't), the cardinals may want to put in for a RH center fielder, like chris young, especially if the diamondbacks fall out of the race in the NL West over the next few weeks.

the cardinals could be best served by improvement (as always) at second base. however, it's very hard to see a trading partner with a significantly better option than the cardinals' time share at second. the only remotely possible improvement at second by trade would likely be aaron hill from the diamondbacks, hoping that he'd keep up the offense he's delivered for them. even though rogers centre is pretty hitter-friendly, hill stumbled in his last few seasons there, afflicted by a .196 BABIP in 2010 and a .242 BABIP in his partial season in Toronto in 2011. he turned those numbers around promptly in the desert, putting up a .376 wOBA in his partial season in Arizona in 2011, and a .361 wOBA so far this year. i don't know that hill is even available, however, unless the diamondbacks slip farther behind.

if jon jay and chris carpenter prove healthy, the cardinals could look to improve the bullpen. whether the bullpen's travails are misfortune in a small sample size or bad performance, almost any serious look at the bullpen indicates it is below league average. acquiring a top-notch bullpen arm could be a boost, but every contender will be looking for bullpen help. whether the price of midseason help in the bullpen merits the price for a fairly small boost seems doubtful, unless we can find an undervalued reliever, or a team with whom we can deal from a surplus. color me dubious about finding such a trade, but certainly any continuing needs in the rotation or center field trump any bullpen needs. we're still in wait and see mode on the trade deadline.