What Separates Spencer Strider From Hunter Greene

Here’s an example of why baseball is complicated. By a lot of measures, Hunter Greene and Spencer Strider are near-identical players. Both are righty pitchers who rely on their four-seam fastballs, for good reason; they’re producing some of the highest average fastball velocities we’ve ever seen from a starter, pushing the limits of what’s possible. They’re doing that as rookies, with Greene, 22, only a year younger than Strider. These are bright futures we’re talking about.

And yet, the on-field results couldn’t be any more different. As of this writing, Greene owns a 5.43 FIP in 85.1 innings, which is close to replacement level. Meanwhile, Strider has been thriving in the Braves’ rotation, with a 2.07 FIP in 46 innings so far as a full-time starter. Baseball is complicated, because even when two pitchers execute a similar blueprint, one can end up with better numbers than the other. With Strider and Greene, something isn’t adding up.

What’s biting Greene this season? He’s still striking out a ton of batters, and while he does walk quite a few of them, it’s not at a catastrophic rate. In these regards, he still resembles Strider. The problem is that hitters have absolutely feasted against his prized fastball. The wOBA on contact against Greene’s heater is a staggering .573 — higher than Aaron Judge’s overall wOBAcon (.523) this season. As for Strider? In an identical sample of 114 batted balls, he’s limited opposing hitters to a .337 wOBAcon. Results-wise, it’s the hard contact (or lack thereof) that has separated Strider from Greene.

For anyone who’s watched either pitcher, this probably isn’t news. What matters more to us is the why — as in, why is Greene more susceptible to hard contact than Strider? It is true that Greene’s fastball command is a tad inferior to Strider’s, which might have had an influence. I know there are models out there, but let’s keep things simple. Greene has thrown 51.9% of his fastballs for strikes. Strider, with 57.4% strikes, has found the zone with more regularity. But hitters don’t produce loud contact against pitches outside the zone; they pounce on strikes. And if we look at the rate of fastballs located up in the zone — 30.3% for Greene, 29.8% for Strider — the two don’t look all that dissimilar.

If anything, the strike-throwing Strider should be an easier target — that is, assuming we’re comparing fastballs of equal quality. But it’s an assumption that couldn’t be any farther from the truth! You may have read or heard about how Greene’s fastball has a suboptimal shape, and how it’s been holding him back. Then again, what does “shape” exactly mean in this context, anyways? Essentially, it’s a catch-all term denoting a pitch’s characteristics besides velocity. Movement is what constitutes shape, but to others, variables like release point and extension also fall under the umbrella.

We’ll get to those, too, but let’s start off with movement. Over the years, we’ve realized two things: that a fastball’s vertical movement is far more important in eliciting whiffs than horizontal movement, and that extreme amounts of either movement type help limit hard contact. Both Greene and Strider feature above-average carry on their fastballs by big league standards, but Strider edges out his fellow rookie by an inch and a half. Is that a big difference? Think of it this way: By fastball vertical movement, Strider is in the same company as Shane McClanahan and Yu Darvish. Down below, Greene is in the same company as, well, Kris Bubic and Hansel Robles.

Those are cherry-picked names, but you get the idea. What Greene does have going for him is horizontal movement — six additional inches of arm-side run compared to Strider, to be exact. It’s not much help, though. Because it’s accompanied by a generic amount of vertical movement, Greene’s fastball doesn’t zig or zag in a direction hitters aren’t anticipating. Rather than miss the barrel of bat vertically or horizontally, it’s more likely to sail right into it. When that happens, it’s no wonder Greene is greeted with thunder off the bat.

Movement isn’t everything, however. A pitcher can still succeed with an underwhelming fastball if he’s unique in a certain regard, such as release point. Consider the Mariners’ Paul Sewald, who is one of the most deceptive pitchers in the league. Despite possessing average-ish ride, his 92-mph fastball still garners whiffs because opposing hitters aren’t accustomed to that shape from his low arm slot. Subvert expectations, and life becomes easy.

Unfortunately, Greene isn’t a Sewald-esque pitcher, and he probably never will be. The flame-throwing righty is dependent on a fairly high release point to generate movement, but it’s a combination that hitters are used to. In contrast, Strider manages more vertical movement from a lower release point. For a visual example, here’s a side-by-side comparison between Greene and Strider at the point of release:

Thought Greene has the lower arm slot, you can tell from the position of the ball against the stadium grass that he has the higher release point. On a related note, Greene is listed as 6-foot-5 on Baseball-Reference, whereas Strider is listed as 6-foot-0. For the latter, a lack of height actually works in his favor, as Strider is able to get on top of the ball without having to drastically raise his release point. You can also tell from their respective deliveries that Strider releases the ball closer to home plate than does Greene. The benefit of added extension is straightforward: To a hitter, the pitch appears faster and is thus trickier to deal with. Triple digits from Strider is more devastating than triple digits from Greene.

These are a lot of details and numbers, so as a recap, below is a table comparing the relevant metrics on the two rookies’ fastballs. Why is Strider earning such better results on his heater? Because it’s superior in a lot of ways:

Long ago, scouts judged fastballs based on their velocities. The harder a pitcher threw, the better his fastball. We’re still inclined toward velocity, and it’s through this simple and widespread measure that Strider and Greene seem equal. But dig deeper, and the superficiality begins to fade away. Compared to Greene, it’s Strider who not only creates more vertical movement, but also unleashes it through a lower release point and lengthier extension. His approach angle is flatter as a result, giving the illusion of rise.

The importance of vertical movement, release point, and extension isn’t revolutionary — the baseball industry caught up to it years ago — and yet, I’m not sure if these variables are being emphasized enough. This year, our top prospect lists pegged both Greene and Strider as having 80-grade fastballs. Eric Longenhagen and others did take shape into consideration, and I have the utmost respect for their hard work. But in retrospect, I don’t think Greene warrants the coveted 80 mark. His velocity is generational, but it doesn’t quite make up for the myriad flaws he has, a fact reflected in his inability to stifle opposing batters.

This doesn’t mean Greene’s fastball is bad by any stretch of the imagination — sitting 98–99 mph, how could it possibly be? And I certainly don’t believe he’ll be saddled with a 5.43 FIP for an entire season; his talents and athleticism are too great for such an abysmal total. On the flip side, Strider probably isn’t a low-2 FIP guy moving forward. Though his command of it is a smidge worse, Greene’s slider has been a more reliable weapon than Strider’s, and it’s Greene who has the prototypical starting pitcher frame, not the relatively diminutive Strider. Those are aspects we should consider as well.

But this article is primarily about their fastballs, and why one has outshined the other despite initially receiving less fanfare. That Greene’s heater has been hittable seems like a mystery at first, but upon further inspection, perhaps it really isn’t. Velocity matters, but more importantly, so does shape. As they say, the devil is in the details. Pitching is no exception.

All statistics in this article are through games of July 13.