Life is supposed to be about trade-offs. At least it is for most of us. Eat more things that taste good, and realize the consequences the next time you weigh yourself. But for Jacob deGrom, it seems as if the normal rules of life don’t apply. He keeps getting older, but somehow keeps throwing the ball harder. And this season, his fastball is getting fat on horizontal movement without sacrificing any of its vertical hop.
While it has only been two starts, the Mets’ ace has continued a trend that started in Spring Training by throwing his four-seam fastball with significant more run (movement toward the arm-side) than he ever has before. In fact, he averaged more horizontal movement in each of the past two games than he has in 107 of his previous 109 starts.
This might be why he has upped the usage on his four-seamer this month. Hitters gearing up for a 100 MPH fastball don’t expect a pitch like that to suddenly dart from left to right. And they definitely don’t expect it to rise at the same time.
It’s almost like deGrom has added a completely new pitch to his repertoire, especially when he can seemingly tinker with the amount of movement he generates, making the same pitch look slightly different.
Watching Jake’s fastball in flight is like watching Spider-Man swing vertically and horizontally through the Manhattan street grid in the movie-inspired video game where gravity is an observer instead of an acting force.
But just like Spider-Man doesn’t actually fly, fastballs don’t truly rise; the ones described as such simply drop less than a typical pitch. This “rising” action is created by optimizing backspin on the ball. Besides grip and wrist orientation, a pitcher best facilitates rise with their arm slot. Generally, pitchers with an arm slot that is more over-the-top have an easier time creating efficient backspin and reducing drop than those who throw from a slight angle.
This is best visualized using a clock. As you can see in the graphic below, all else being equal, a right-hander usually trades “rise” (vertical drop) for “run” (arm-side movement) by altering the pitch’s spin direction (or tilt) from 12:00 or 1:00 toward 2:00.
For deGrom, his fastball had a spin tilt around 1:00 last season (as labeled “A” in the graphic above). As expected, his spin tilt is a little lower through the first two startsof his current campaign, but only slightly to around 1:15 (more on this in a bit). For a normal pitcher, all else being equal, by changing the spin tilt from 1:00 toward 2:00, it would result in more armside movement at the cost of vertical drop. You can see this depicted in the scatter plot above with the point labeled “A” shifting to the point labeled “B”.
We can illustrate this concept using every Mets fan’s best friend, Edwin Díaz. He has added nearly 15 degrees to his spin direction since 2018 (or about 30 minutes from 1:00 toward 2:00 using the clock scale). And his horizontal movement (left graph below) has skyrocketed at the expense of his vertical movement (which is depicted relative to similar fastballs at his velocity to better showcase the downward trend).
But if we look at this same relationship for Mr. deGrom, we find a completely different story. Despite adding significant horizontal movement to his fastball over the past few seasons, and particularly this season, his vertical movement remains well above league average relative to his release point and sudden increase in velocity.
Let’s now return to our graphic from earlier and add an extra point. Instead of moving from “A” to “B” on the scatter plot below, deGrom has somehow moved from “A” to the blue circle. He has done so without a drastic change in his release point and with only a slight variation in his spin tilt.
What does this all mean, in plain English? Looking at the available data on his fastball, deGrom has improved two key metrics: velocity and spin efficiency. By throwing the ball faster, it has less time to respond to gravity, which helps its raw vertical movement metric. And by throwing the ball with more active spin (94% compared to 89% last season), he is also boosting the overall movement on the pitch, both vertically and horizontally.
However, none of these changes are drastic, which leads me to believe he is also doing something the data isn’t capturing, and that is changing his grip and/or wrist orientation upon release. By manipulating how the ball comes out of his hand, he can defy some of the conventional indicators of horizontal versus vertical movement to produce a pitch that rises and runs like an athlete training for a marathon.
BOTTOM LINE: At 32 years of age, with multiple Cy Youngs on his mantle, Jacob deGrom continues to evolve in ways that even the fanciest of metrics have trouble explaining.