Yesterday at ESPN, Mark Simon posted a heat map for Salvador Perez. It showed that Perez, in his short time in the majors, swung at a few balls out of the strike zone with many of them going for hits. Simon compared his plate disipline to Vladimir Guerrero. I decided to look a little further to see if the Vlad comparison was valid.
To begin with, it needs to be understood that Perez's MLB sample size is barely relevant. It would be nice to have a season or two worth of data, but we don't right now. One fact that is for sure is that Perez, does not walk much. He walked (NIBB) only 5.2% of the time in the minors. For comparison, Hosmer walked (NIBB) 10.7% of time, Moustakas 5.9% and Giavotella 9.6%. Perez is not much of a walker yet.
Further along in the article, Simon mentions:
Perez swung at 40 percent of the pitches thrown to him outside of the strike zone. That's a very high rate, comparable to the likes of Vladimir Guerrero and Pablo Sandoval.
As much as I like Mark (he was the person that got me published in ESPN the Mag), he is taking a liberty in the comparison. Here are the players and the percentage of time they swung at pitches out of the strike zone according to Fangraphs (min 100 PAs):
Perez does swing out of the zone a bit, but it is ~5 percentage points less than Guerrero and Sandoval. Perez's free swinging ways is closer to a couple of other Royals, Francoeur and Betancourt.
Another observation I had from the graph was that Perez hit balls that were generally close to the zone. To see how far he chases balls out of the zone, here is how often he swings at pitches compared to the league average (20 pitch league regression). The scale is percentage decimal format (.1 = 10%) and is the percentage point difference compared to the league average. The graphs are from the catcher's perspective.
Against LHP, he is basically league average. Against RHP, he does chase the ball 10% more than the rest fo the league off the plate. His discipline is not that bad. Now for some bad ones, here are the same graphs for Jeff Francoeur.
Perez may expand the strike zone a bit, but he is not in the Francoeur zone yet.
Finally, here are the Run Value heat maps that show how many runs are expected to be scored for each pitch in that zone). These graphs are compared to league average.
As it can be seen, Perez crushed LHP (2011 line: 0.484/0.543/0.742) in all part of the strike zone last year. Against RHP (2011 line: 0.291/0.309/0.402), he hits the ball best when it is low and inside or high and away.
With a limited amount of MLB data, Perez does expand the strike zone. The zone expansion was not to the level of Guerrero and Sandoval as it was stated at ESPN. Hopefully though he does show a little more discipline so Betancourt and Francoeur are no longer possible comparisons.