After Jose Altuve scorched the Brewers for four hits in five plate appearances yesterday, I did a little research. I have been following his major league career a tiny bit, as I own him on a fantasy team. I picked him up after Kevin Goldstein’s obsession with him last season. Basically, he’s a little guy that can hit but lacks any sort of plate discipline. In fact, that’s exactly what happened last year. In 234 PAs, he had a .276 batting average (not bad for a 21-year old) and a 2.1% walk rate. However, this year in 77 PAs, his walk rate is an above-average 9.1%. Derek Carty found that walk rate stabilizes after 168 non-IBB/HBP PAs, so the sample size is not yet large enough, but it is about halfway there.
Obviously, this realization required a deeper look. That very day, Astros beat writer Brian McTaggart noticed that while the Astros batting average and slugging percentage through 19 games are very similar to last year, their on-base percentage is 20 points higher. Astros front-office analyst Mike Fast replied to that post with “Interesting comparisons. I love seeing that OBP where it is this year so far.” Of course you do, Mike.
So what is leading to the Astros increased on-base percentage and is it a result of the new Jeff Luhnow-run front office? Well I can’t answer that second question because I’m not on the inside, but I may have some input into the first. I do believe that there is a systematic change in the Astros hitters’ approaches this season.
The first difficulty in looking at this is that so many of the Astros hitters are fairly young, so they don’t have a good amount of MLB PAs to compare this season with. However, since walk rate does stabilize so quickly, the numbers should still be helpful. I compared each player’s 2012 plate discipline numbers with their 2011 ones. Jason Castro and Justin Maxwell did not play in 2011, so I used their 2010 numbers instead.
I found the top 12 hitters in PAs for the Astros this season, excluding rookie Marwin Gonzalez. Then I compared their BB%, O-Swing%, Z-Swing%, Swing%, O-Contact%, Z-Contact% and Contact%. between 2011 and 2012. You can read about the definitions of these stats on Fangraphs (their custom leaderboards and player lists made this very easy). I used the pitch-fx versions of each of them.
This is what I found. Positive numbers mean the number is higher in 2012 than it was in 2011. (I apologize for the poor formatting)
The baseball statistic “at-bat” drives me crazy. It is often used to describe any time a batter goes to the plate; however, that is not how it is calculated. Allow Joe Posnanski to elaborate:
Now, subtract the walks. No, seriously, just subtract those. We don’t care about those.
Now, subtract the hit-by-pitches. Get rid of them.
Now, subtract the times that the player hit a fly ball that allowed a runner to tag up and score from third base.
Now, subtract the times the batter bunted a runner from first to second base, or second to third, or third to home but still made an out. Do not subtract the plate appearance if the batter successfully made it to first base. Do not subtract it if he hit a hard smash that accomplished PRECISELY THE SAME THING as a bunt. Do not subtract it if he hit a check-swing dribbler that was KIND OF like a bunt but did not seem from the press box to be a purposeful bunt.
Remember to include the times he reached base but only because of a defensive blunder.
OK, you have that number? We call those “at-bats.”