Jacob deGrom is throwing a lot more fastballs and it’s working

Since the start of the 2018 season, Jacob deGrom has been baseball’s best pitcher by a convincing margin. Pitching to a 1.99 ERA/2.22 FIP/2.69 xFIP in 534 innings, his 21.1 fWAR not only paces the entire league, it is 3.6 wins better than the next best pitcher, Gerrit Cole.

His performance has netted him two Cy Young Award wins in 2018 and 2019, as well as a third place finish in the pandemic-shortened 2020. So far in 2021, at least on a rate basis, he may be having his best year yet. Currently, deGrom leads the National League with 2.4 fWAR despite throwing 20 fewer innings than the four pitchers who trail him, due to a brief IL stint.

deGrom has made a few changes to his arsenal in 2021. He hasn’t added a new pitch, nor is he throwing his secondary pitches more. Rather, deGrom has dropped the curveball and increased his fastball usage dramatically.

Baseball Savant

Throughout his career, deGrom’s four seam fastball usage has hovered in the range of 39.6 percent to 48.1 percent. In 2021 however, he is throwing it at a 64.6 percent clip. Along with the increased usage, deGrom has increased its velocity very year since 2016.

Baseball Savant

In his first Cy Young year, deGrom’s 96 mph average exit velocity ranked in the 90th percentile. Since then, he has increased it three whole miles per hour, averaging 99 on the fastball in 2021, putting him in the 99th percentile. It is truly remarkable considering the workload as well as the fact that deGrom is now 32 years old.

But that is not all. Not only has the velocity been continued to get better, so has the command. Take a look at deGrom’s heat map from 2020.

Clearly, the game plan is to let the fastball play up in the zone. This idea has remained in 2021, but with a slight alteration.

deGrom is still keeping the fastball up in the zone, but it appears that he is making a more concerted effort to keep the ball to his glove side. Using Baseball Savant’s search tool, thanks to deGrom’s increased fastball usage, I found that 40.9 percent of his total pitches are fastballs to the upper and glove side part of the zone, compared to just 22 percent of total pitches a year ago with decreased fastball usage.

This is especially interesting because, generally speaking, pitchers tend to have more success with fastballs to their arm side, unless they have cutting movement, which deGrom does not. While deGrom’s fastball has always generated a high rate of swings and misses, it jumped up substantially in 2020 to 36.8 percent from 26.8 percent the year prior. This year he has been able to repeat this success, maintaining a 36 percent rate of misses per total swings.

But in the upper glove side zone in particular is where deGrom has has the best results. In 2020, he had a 39.2 percent swing and miss rate on fastballs in this area. This might explain both his increased fastball usage in this area as well as his fastball usage overall, as his fastball swing and miss rate on these pitches has increased to 40.6 percent in 2021.

Coincidentally, deGrom has also increased the swing and miss rates on his secondary pitches as well, his slider rising from 44.6 percent to 51.7 percent and his changeup rising from 42.9 percent to 45.9 percent, so it seems that throwing his fastball more has made his secondaries more effective as well.

For now, it is hard to say whether deGrom will continue to throw his fastball as a nearly 65 percent clip, but it is pretty clear to see why he has increased its usage as well as where he is locating the pitch. In today’s era, even pitchers with great fastballs see increased usage in secondary pitches, but deGrom has done the opposite so far in 2021.

Brian Menéndez is a contributing writer for Beyond the Box Score, as well as a senior writer for DRaysBay. Additionally, he has been featured in FiveThirtyEight and The Hardball Times. You can find Brian on Twitter at @briantalksbsb.