Mookie Betts is having a poor season, by his standards. Batting .261/.342/.435/.777 (102 OPS+) is fine, especially when combined with his excellent defense, but is a big step down from his 2016 MVP runner-up season (.318/.363/.534/.897, 133 OPS+).
Looking at PITCHf/x data gives some clues to his offensive struggles this year and offers a little hope that he may be coming around in time for the off-season. I split the pitches Mookie has seen into three families (fastballs, breaking pitches, and off-speed pitches) and charted their location in and around the strike zone, each year since his 2014 rookie season (when he had 213 plate appearances). I split the region around the strike zone into 25 sections, and calculated his total bases per pitch in each one. I then compared Mookie’s numbers to those of all other right-handed batters that year.
Each chart shows Mookie’s effectiveness, relative to the average right-handed batter. Red means better than average; blue means worse. In the background, shown as contour plots, are the overall pitch location for each type.
Looking first at pitch location, especially fastballs, it’s easy to see the book on Betts. He has extraordinarily quick hands and can crush fastballs on the inside half of the plate, but is relatively weak on the outside half. In 2014 and, especially, 2015, pitchers targeted the middle of the plate against him, but by 2016 the pitches were starting to move to the outside, and in 2017 pitchers have pounded the outside half of the plate — not coincidentally, targeting the precise area of the plate where he is weakest.
Betts has a larger preferred region for breaking pitches, covering most of the strike zone, but down and outside is relatively weak, and breaking pitches have also moved down and outside to him; in 2017 they have clustered tightly in the bottom outside corner.
But the most interesting point is in the offspeed pitches. In previous seasons, Betts has offspeed very well, but in 2017 the whole offspeed chart is a chilly blue — much worse than average. Unlike fastballs and breaking pitches, offspeed location hasn’t drastically changed this year; he is still seeing offspeed pitches in the lower half of the strike zone, which he has hit well in previous years.
Here’s a summary of Betts’ production against various pitch families both per year since 2014, and by month through 2017. The dotted lines show the average right-handed batter’s production:
In previous years, Betts has produced well above average numbers against offspeed pitches, as well as other pitch families. In 2017, he has been far worse than average overall. In April of 2017, he saw 38 changeups, and didn’t get a single hit off them (16 balls, 7 in play for outs, 6 fouls, 6 called strikes, and 3 swinging strikes).
This looks like a timing issue. Hitters need to wait longer on outside pitches to hit them to the opposite field. A good example of this is Xander Bogaerts flipping hits to right field. When hitters try to pull the outside pitch, they usually hit a harmless grounder or pop it up for an out. This is especially true for slower pitches, like changeups, since the batter has to wait even longer for them. The possible good news is that, after tweaking his batting stance a little, Betts has been more successful against offspeed pitches in September, albeit in a small sample size. Slightly surprisingly, opposing pitchers haven’t noticeably increased the use of offspeed pitches against Betts this season (probably because the pitch typically loses effectiveness when it’s seen more often).
(These don’t sum to 100% because a few pitch types — mainly knuckleballs — don’t fit into any of the categories.)
Throughout most of the season Betts has hit fastballs and breaking pitches reasonably well, so if he continues to do so and has turned the corner on offspeed pitches, he is well set for the rest of the season and the offseason. If not, he is just a very good player instead of an MVP-caliber one.
Featured image courtesy of Mitchell Layton/Getty Images