Jacob deGrom’s fastball is better than ever; these three under-the-radar factors help explain why


New York Mets ace Jacob deGrom will enter his start on Monday night against the Atlanta Braves with some impossible seasonal numbers.

Through 11 starts, deGrom has a 0.54 ERA and a 724 ERA+ (meaning he is 624 percent better than the league average) to go along with his 13.88 strikeout-to-walk ratio. He’s punched out an astounding 47.8 percent of the hitters he’s faced, all the while walking just 3.4 percent. He’s even contributing with the bat, having recorded more runs batted in of his own (six) than earned runs allowed (four). 

Various injuries have restricted his innings load, yet his brilliance has him tied with Yankees‘ star Gerrit Cole for the fourth most Wins Above Replacement among pitchers — and Cole, who has been quite good himself, has accumulated 22 more innings.

The “don’t fix what isn’t broken” sentiment tends to reign supreme in pro sports. Yet despite having won two of the last three Cy Young Awards (and finishing third in the other year), deGrom has made a noticeable change this season to his approach. Whereas he’d never thrown his four-seam fastball as much as 50 percent of the time in a prior year, he’s ramped up his usage to 61.3 percent entering his Monday outing.

Tom Seaver used to say that the fastball was the first and second most important pitch in baseball, and deGrom seems to have taken that observation to heart. At minimum, his heater is the engine propelling him to such lofty heights, as he has permitted the fifth lowest batting average on four-seamers in the majors. Explaining deGrom’s fastball dominance would seem to be a straightforward endeavor: he throws at the velocity of a closer with the precision of a starter.

That statement is true, of course: deGrom’s 99.2 mph average velocity is the highest among qualified pitchers, some 1.4 ticks quicker than second-place Sandy Alcantara, and while command isn’t quantifiable, his aforementioned walk rate speaks to his marksmanship. Still, there’s more to deGrom’s fastball than just those two traits. 

With that in mind, let’s highlight three other contributing factors. (Note, most of the stats in this article are from TruMedia.)

1. Extension

What is it? Common sense (and all those train-related math problems in school) dictates that if two balls are thrown at an equal velocity, but one is released closer to its destination, then that ball will arrive quicker. That, essentially, sums up the concept of “extension,” which measures the distance from the rubber to the pitcher’s release point in feet and inches.

How does it benefit deGrom? As it turns out, deGrom has one of the deepest release points in Major League Baseball. Although he’s listed at 6-foot-4, he’s able to generate 6.96 feet of extension, ranking him fourth among qualifying pitchers, behind Tyler Glasnow, Zack Wheeler, and Freddy Peralta

By releasing the ball closer to the plate, deGrom toys with the batter’s perception of how quickly the pitch is moving. Quants have figured out how to measure a pitch’s “effective velocity,” and, sure enough, deGrom leads the majors in that category, at 100.4 mph. To put that number into perspective, his 90th percentile raw velocity this season is 100.5 mph. It’s no wonder why batters have a hard time catching up.

2. Deception

What is it? “Deception” is often used to describe pitchers with funky releases, or herky-jerky deliveries. Here, we’re applying “deception” in a different manner by examining how the batter perceives the pitch’s movement; specifically, we’ll be using a metric called Vertical Approach Angle, which measures (in degrees) how a pitch is moving as it enters the zone. The easiest way to think of VAA is to adapt an NBA mindset: being an outlier is good, because pitchers can leverage that effect by pitching a certain way, while being in the middle is not ideal.

How does it benefit deGrom? Wouldn’t you know it, deGrom appears near the top of another leaderboard. His four-seamer’s VAA is -4.03 degrees, or the second-lowest in the majors behind the aforementioned Peralta. (The highest mark among starters belongs to Houston’s Zack Greinke.)

How, exactly, does deGrom generate such a low VAA? It’s a combination of where he releases the ball and where it crosses the plate. It’s fair to categorize deGrom’s arm slot as being low three-quarters, and that, married with how far he gets down the mound, leaves him with one of the lowest release points among starters. At the same time, deGrom elevates his heater nearly half the time. The ball is often traveling on a low-to-high track, in other words, creating an optical illusion batters seldom overcome. 

3. Break

What is it? Not to be confused with movement, break is how far a pitch deviates from the path of a pitch delivered on a straight line. (Some metrics incorporate gravitational effects, some don’t.) For our purposes, we’ll be referencing Induced Vertical Break (IVB), a measure that helps identify pitches with great “rise.”

How does it benefit deGrom? Believe it or not, deGrom isn’t among the best at something. His IVB is only 16.3 inches, putting him in line with a league-average mark. Still, that puts him in the same grouping as the pitchers he shares deep release points with (Glasnow, Wheeler, and Peralta), and it’s not a blemish on the pitch.

If anything, deGrom’s four-seamer IVB being just average amplifies how many other areas the pitch excels in: velocity (raw and effective); extension; deception; and command. It’s no wonder, then, why deGrom’s fastball is one of the best in baseball, or why his increased reliance upon the pitch has left him in rare air.





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