Guerrero, Andrus, and Swing%

One of my favorite stats pages on FanGraphs is the Plate Discipline Leaderboard. In it, you can find out which hitters swing at pitches out of the strikezone (O-Swing%), make most contact when swinging (Contact%), or see the most pitches in the zone (Zone%). In particular, Swing% tells us which batters swing at the most pitches or the fewest pitches. It should not be surprising that Vladimir Guerrero is the leader in this stat this season, swinging at 60.7% of all pitches. On the other end of the leaderboard, his Rangers’ teammate Elvis Andrus is 6th this season in the least percentage of pitches swung at with 36.9%.

I was curious to see how Guerrero and Andrus differed in Swing% based on different pitch types: fastballs, sliders, curveballs, and changeups. I modeled each batter’s Swing% vs. each pitch type by handedness and plotted heat maps for each one. Turns out I came up with 16 graphs, so let’s take a look at four of them at a time. The first four are Guerrero and Andrus against RHP and LHP fastballs:

Guerrero saw 2335 RHP fastballs and 904 LHP fastballs since 2007 while Andrus saw 1522 RHP fastballs and 541 LHP fastballs since his debut. The levels on the right can be read as percentages, so 0.8 indicates swinging at 80% of pitches. Guerrero loves to swing at fastballs from both hands, swinging at 80-90% of fastballs up and in while inside the zone. The centers of these fastball hotzones are similarly located for Andrus, but he swings at far fewer fastballs, maybe topping out at 65-70% in his hottest spots. Let’s look at the next four, which are against RHP and LHP sliders:

Guerrero saw 1040 RHP sliders and 174 LHP sliders since 2007 while Andrus saw 429 RHP sliders and 88 LHP sliders since his debut. Again, Guerrero hacks at a lot of sliders, particularly low and inside sliders from LHP. It seems that Andrus is also pretty vulnerable in swinging at low LHP sliders, but many of these are low and outside instead for the young right-handed hitter. Let’s look at how the teammates swing at RHP and LHP curveballs:

Guerrero saw 441 RHP curveballs and 208 LHP curveballs since 2007 while Andrus saw 262 RHP curveballs and 105 LHP curveballs since his debut. Similarly, both Guerrero and Andrus swing more at LHP curveballs than they do against RHP curveballs. Remember, these plots are looking at Swing% and are not indicative of whether the result of the swing was a swinging strike or an extra base hit. However, you can safely assume that a low breaking ball out of the zone is not a wise pitch to swing at (well, except that Guerrero is notorious for making solid contact off pitches out of the zone, but that’s for another post). Finally, let’s look at Guerrero and Andrus swinging against RHP and LHP changeups:

Guerrero saw 313 RHP changeups and 278 LHP changeups since 2007 while Andrus saw 237 RHP changeups and 212 LHP changeups since his debut. The colors in these plots look similar to that of fastballs, except that the epicenters of the hot swing spots are lower for changeups than for the high fastballs. Again, Guerrero isn’t afraid to swing at inside RHP changeups, swinging at 90% in some areas, while Andrus lays more of these pitches off, swinging at about 50% of changeups throughout the strikezone.

A lot of interesting questions could be asked from here in terms of comparing Guerrero and Andrus. For instance, how often does Guerrero make contact off of low sliders compared to Andrus when he swings? How much damage does Guerrero make off of changeups down the middle compared to Andrus? Is Guerrero swinging at too many pitches or is Andrus swinging at too few? This season, Guerrero has made contact 80.6% of the time he swings, while Andrus, although swinging at many fewer pitches, makes contact 88.4% of the time when he does.

A quick look at pitch type values can also tell us which hitter is more successful against which pitch types. Obviously, Guerrero has much more power than Andrus does and is particularly effective at hitting curveballs and changeups, with a wCB/C of +6.85 runs and a wCH/C of +4.68 runs — good for 1st and 2nd in the majors this season. However, the one pitch that Guerrero is worse at hitting this season is the slider, with a wSL/C of -0.52 runs (he has been more successful in the past).

Much more information can be gleaned if we look at contact, batted ball, or SLG% plots. For now, it’s fun to marvel at visualizations of vastly different approaches in plate discipline.