Being that we aren’t quite out of April, it’s a little early to read into most statistics but certain numbers become meaningful before others. Under the definition of ‘sample size’ in FanGraphs’ glossary, you’ll find a list of stats and the corresponding sample sizes needed before they achieve reliability. For offensive players, the first of those numbers is swing percentage, or how often a given hitter decides to swing the bat.
Theoretically, swinging less often is viewed positively since it suggests that the hitter could be cultivating a more disciplined approach. Selectivity is important for two reasons: (1) Hitters have a better chance to reach base via the walk if they resist swinging at pitches outside the strike zone, and (2) abstaining from pitches that would likely induce weak contact allows them to avoid making easy outs.
According to FanGraphs, swing percentage stabilizes after 50 plate appearances. Most of the Cardinals’ regulars have accumulated enough plate appearances for us to visit this stat and observe whether any obvious trends have emerged. It’s important to note that even though a trend is established after the stabilizing threshold (in this case, 50 PA) occurs, it does not mean that said player will continue to perform at the new rate, just that we can expect his performance to trend in that direction in the future.
The chart below portrays those Cardinals who have stepped to the plate at least 50 times this season and it pits their 2012 swing percentages (blue line) against their career swing percentages (red line). For the record, I’m using the PITCHf/x plate discipline numbers available at FanGraphs (as opposed to BIS data) for the reasons outlined by Colin Wyers in this Baseball Prospectus article. WARNING: I augment each individual player description with other statistics (strike out rate, line drive rate, walk rate, etc.) that have not yet stabilized, so while they are adequate descriptions of what has transpired thus far, they do not imply trends… yet.
Rafael Furcal and Carlos Beltran are swinging at fewer pitches overall but I’m not convinced that this is indicative of an overall change of approach at the plate. They are both well-established veterans unlikely to drastically change their approach given past, and in the case of Beltran, recent successes. The discrepancy in their approaches can likely be attributed to the fact that they’ve seen fewer pitches in the strike zone this season. Beltran has seen 2.4% fewer pitches in the strike zone while Furcal has seen 4.7% fewer (compared against entire career).
Yadier Molina is another example of a guy who is seeing fewer pitches inside the strike zone (44.7%) in 2012 than in his career (51.2%). It’s a good sign then that he is swinging less often. His selection process seems to be working as an impressive 29.4% of his balls in play have been line drives. His ability to perform at a level equal to or within shouting distance of 2011 would go along way towards justifying the contract that will pay him ~$15 million/year through 2017. I noticed yesterday morning that ZIPS’ updated 2012 projection (.346 wOBA) for Molina is now extremely close to his overall production (.349 wOBA) in 2011; see @bgh’s post at VEB for more information about Yadi’s offensive transformation.
David Freese is swinging slightly more often than his career to date. While his production has been fantastic thus far in 2012, there are some worrisome underlying numbers. For example, he’s only walking 5% of the time but striking out 27.5% of the time, while much of his success is predicated on a high BABIP (.417) not likely to be sustained by a line drive rate that is only slightly higher than league average. Of course, walk rates and strike out rates do not stabilize until 200 and 150 plate appearances respectively, so things might look differently by the time we get there.
Matt Carpenter is confirming what we already knew. He doesn’t swing a whole lot. He doesn’t wear batting gloves. Moving along…
In spring training, I observed that Daniel Descalso was taking more walks than he had in the past, and the trend seems to have carried over into the regular season. Descalso is swinging at 7.5% less often than he has in the past despite seeing the same amount of pitches in the zone. As he approaches 200 plate appearance, it will be interesting to see if this trend continues. Since his success is predicated more on luck on balls in play, it would behoove him to adopt more patience at the plate so that he has more than one way to get on base.
Jon Jay is interesting. Even though he has seen a greater amount of pitches within the strike zone, he has swung less often, and he seems to be laying off the right pitches. While the average major leaguer swings at roughly 28% of pitches outside of the strike zone (also close to Jay’s career rate), he has only chased 18% of such pitches in 2012.
With the exception of Freese, the Cardinals seem to be swinging at fewer pitches overall. This is encouraging since several of them have seen a reduced amount of pitches within the strike zone. Perhaps McGwire’s emphasis on looking for a pitch in a certain area of the strike zone is taking root.