At FanGraphs, Steve Slowinski called attention to the fact that many players are now reaching significant thresholds in playing time. Thanks to research from Pizza Cutter (all links can be found here), we know that players’ skill sets tend to stabilize after a certain number of plate appearances or batters faced. Steve explained what is meant by this well:

When I say “stabilize”, I don’t mean that these rates won’t change at all over the remaining course of the season. Instead, all it means is that once a player approaches these sample sizes, you can consider that there’s something more than just random variation going on: there’s some underlying change in a player’s approach/skill level/process/etc. in play as well. Matt Garza isn’t guaranteed to finish the year with a 12 K/9 rate because his strikeout rate has “stabilized”, but at the same time, I wouldn’t be surprised if his final strikeout rate is higher than what it’s been in the past.

So this isn’t to say that players will continue performing at current levels, but we can infer an upwards/downwards trend in approach or skill, even at these relatively small sample sizes.

If you followed the link to the FanGraphs article, you know where I’m headed. Most batters have now accumulated enough plate appearances to tell us something about their swing rate (50 PA) and contact rate (100 PA), while most pitchers have now faced enough hitters to lend insight into their strikeout rate (150 BF) and groundball rate (150 BF). While Steve’s article takes a look at all players across MLB, I thought it’d be useful to narrow the scope to our team.

Below is a graph for the Cards’ position players who have amassed enough plate appearances to be included. You can see the MLB average at the top of the bar graph. Numbers for 2011 are represented by the darker tones while career numbers are found in the bars shaded more lightly. Since Daniel Descalso only had 38 PA before 2011, I only included numbers from this season.

Overall, most guys sit pretty close to their career norms… but let’s take a closer look at a few:

Pre-DL David Freese’s .356 AVG looks pretty suspicious when you compare his contact percentage (71.7%) against the average major-leaguer (80.8%). While he’s making less contact, he’s actually swinging at a higher percentage of pitches than he has in the past. You’d be correct if you guessed that his BABIP (.460) was out of control. Obviously, this cannot be sustained. But Freese is making hard contact when he does put the ball in play as more than 30% have resulted in line drives. That’s not a predictive number but it is a descriptive one.* *

While I look forward to Post-DL David Freese returning to the team in a couple of months (fingers crossed), I remain perplexed by his precipitous drop off in power. In 750+ PA combined between AA and AAA, his isolated slugging percentage never dipped below .200. Nevertheless, it sits at .115 ISO in 398 PA with the big club. In fact, his career “success” to date includes a .396 BABIP.

StatCorner calculates players’ wOBA adjusting for their park and batted ball profile (they use acronym wOBAr). Freese loses 15-pts from his 2010 wOBA and 27-pts from his 2011 wOBA. I’m not saying that his potential contributions are overstated, but his numbers to date don’t exactly reflect his minor league performance (where he displayed decent power), and it’s scary to depend on a supposed power-threat to continue getting on base when he’s mostly relying on hitting singles and striking out 24.9% of the time. If the coaching staff considers this problematic for Colby Rasmus (25.8% career K rate), then why isn’t the same true of David Freese?

While Matt Holliday has decreased his swing percentage by 5.3%, Lance Berkman has increased his offerings by 4.7%. It’s hard to get too worried about either of these players. Holliday has already been worth 2.5 fWAR and there isn’t anything crazy about his batted ball profile (.481 wOBAr – StatCorner’s adjustment for park and batted balls).

Berkman’s case is a little more curious. While he has certainly benefit from a HR/FB rate ~20% higher than league average (only 10% higher than his personal norm), his wOBA (.511) is somehow *lower *than it should be based on StatCorner’s adjustments (.520 wOBAr)! Playing in Busch Stadium has robbed him of a little offensive value. Despite being a negative in the field – but not as horrendous as expected – Berkman has already been worth 2.1 fWAR. In other words, he’s pretty much justified the $8 million contract he signed this winter. The health of his knees will remain a concern until the final out of 2011, but kudos to TLR for continuing to schedule regular days off despite Berkman’s convincing offensive rennaisance.

*What’s next on the horizon? For hitters, strikeout rate, line drive rate, and pitches per plate appearance “stabilize” at 150 TPA; walk rate, groundball rate, GB/FB rate “stabilize” at 200 TPA. Expect me to visit those as the season progresses.*

I’ll try to make some observations about our starting pitchers in the next few days since a few of their rates have also “stabilized”: GB%, LD, and strikeout rate.