You Can’t Fake Exit Velocity

Final week, I spent a couple of articles idly hunting for hitter breakouts. I centered my search on gamers with admirable top-end energy numbers however who reached that summit hardly ever. I discovered that when these gamers elevated their contact price, they improved their general line considerably. I feel that discovering tracks with instinct along with having knowledge to again it up, so I’m general happy with that analysis.

That mentioned, all this downloading and scraping of exit velocity knowledge made me surprise in regards to the reverse aspect of this spectrum: can hitters add energy and get away from the opposite course? Hitters who make a ton of contact however don’t hit the ball with a lot authority really feel considerably capped offensively; in my head, Luis Arraez has a 0% likelihood of handing over a 20-homer season. I didn’t have the numbers behind that, although, so I gathered up the identical pile of information I’d used earlier than and began searching.

The primary factor I discovered from the information is one thing that you just’ve heard over and over: most exit velocity (and Ninety fifth-percentile exit velocity, which I’m utilizing) is sticky. How exhausting you hit the ball in a single 12 months does an excellent job of figuring out how exhausting you’ll hit the ball within the subsequent 12 months.

Extra particularly, I took a pattern of gamers with at the very least 100 batted balls in two consecutive seasons. I sampled from 2015 to ’22, which gave me seven year-pairs, although those involving 2020 have been gentle on qualifying gamers because of the abbreviated season. From there, I requested a easy query: how a lot did every participant’s Ninety fifth-percentile exit velocity change from one 12 months to the subsequent?

Clearly, gamers enhance their exit velocity yearly. Even when their true expertise by no means modified, a laughable assumption, random variance would make some hitters get to their greatest efforts extra often in video games from one 12 months to the subsequent. The query, then, is how a lot a given participant can enhance their exit velocity by, and the way possible that enchancment is.

I got here up with a take a look at that I feel is straightforward and informative. The query I’m asking, basically, is how usually a hitter strikes from one tier of contact high quality to a different, as measured by Ninety fifth-percentile exit velocity. I measured the usual deviation of Ninety fifth-percentile exit velocity throughout the complete inhabitants of hitters with 100 batted balls in every year. Then I checked what proportion of the hitters who performed in each that season and the subsequent improved (or declined) by at the very least one customary deviation.

Which may all sound like a jumble, however take into account it this manner: customary deviation is an effective measure of how extensively the inhabitants varies. You probably have a statistic with big variation from participant to participant, you’d anticipate that statistic would even be noisier for a given participant on their very own. If, then again, there’s virtually no variation throughout the league as an entire, a person participant altering theirs is extra spectacular. Certainly, exit velocity changers are uncommon: solely 4% of hitters noticed their Ninety fifth-percentile exit velocities change by at the very least one customary deviation from one 12 months to the subsequent.

“However Ben,” you may say, “I do not know what which means.” That’s a legitimate level. What’s 4% in comparison with 6%, or 2%, or another quantity I might select of a hat? We have to examine it to one thing extra acquainted to know whether or not 4% of the inhabitants displaying a giant change is a big consequence.

To take action, I enlisted just a little assist from different statistics. I thought-about launch angle tightness, common exit velocity, most exit velocity, chase price, contact price, stroll price, strikeout price, and even wRC+. I used a 150 PA minimal for the non-batted-ball statistics and caught with my 100 batted ball minimal for the remainder. This gave me a baseline quantity to check the modifications in Ninety fifth-percentile exit velocity in opposition to.

If you wish to know why analysts focus extra on top-end energy than common exit velocity, right here it’s in a nutshell. In a given 12 months, 15.8% of batters see their common exit velocity enhance or decline by at the very least a typical deviation. It’s a loud statistic, in different phrases; you may suppose you can inform the distinction between two hitters primarily based on their common exit velocities, however there’s an honest likelihood that you just’re being deceived by variance. Hitters change their common exit velocities by an entire customary deviation 4 instances as often as they modify their top-end energy. One 12 months’s knowledge level might simply be a mirage.

What about launch angle tightness, a way for estimating constant contact? That’s much more variable than common exit velocity: 25% of hitters noticed their launch angle range by greater than a typical deviation from one 12 months to the subsequent. One notice right here: a change in the way in which that Statcast collects knowledge led to a significant change in launch angle tightness measures from 2020 to ’21 (Hawkeye cameras seize the next proportion of batted balls, so meaningfully fewer batted balls had imputed launch angles, which modified customary deviation considerably). Accordingly, I tossed that pair (modifications from 2020 to ’21) out of the dataset.

With regards to batted ball metrics, Ninety fifth-percentile exit velocity stands alone on the prime. For the report, most exit velocity is just too noisy; 13% of hitters modified theirs by at the very least a typical deviation from 12 months to 12 months. I feel that’s a measurement concern, because it’s simpler to crush one batted ball than to crush sufficient to maneuver up your Ninety fifth-percentile mark. That distinction issues much more over less-than-complete seasons; Ninety fifth-percentile exit velocity scales with pattern dimension higher than most exit velocity.

When in comparison with swing-based metrics, Ninety fifth-percentile exit velocity stands out once more (I’m simply going to name it EV95 from right here on out as a result of I’m bored with typing it). 10% of hitters change their chase price by a typical deviation or extra from one 12 months to the subsequent; 7.3% of hitters change their contact price by a typical deviation or extra; 12.3% change their zone contact price by a typical deviation or extra. None of these examine to the roughly 4% mark for EV95.

Naturally, PA-level statistics lag the sphere; they’re the noisiest, which doesn’t shock me. Per the information, 23.3% of hitters change their stroll price by one customary deviation or extra from one 12 months to the subsequent, and 11.4% change their strikeout price by a typical deviation or extra. wRC+ is the noisiest: a whopping 33.8% of hitters see it change by a typical deviation or extra. That makes complete sense to me; it’s attempting to summarize how good you’re at hitting in a single quantity, so innumerable completely different modifications all feed into the identical consequence.

In desk type, you may see EV95’s pre-eminence relating to year-to-year stability:

One nitpicky procedural notice on the above desk: the typical and customary deviation numbers I displayed there are calculated throughout the complete inhabitants for all years from 2015 to ’22. Once I did the precise calculations of which batters modified by a typical deviation or extra, I calculated every year’s customary deviation individually and in contrast modifications to the year-specific numbers.

To be clear, this doesn’t imply that gamers can’t change how exhausting they hit the ball. It’s proper there within the numbers; loads of gamers do it yearly. My favourite instance of that is Lars Nootbaar, who began clubbing the ball when he was already a serious leaguer. However in the event you begin out pondering hitters can develop persistence or contact extra simply than energy, you’re in all probability coming from the fitting place.

There are some significant caveats to this evaluation. This knowledge is for main league hitters; sturdy minor-league batted ball knowledge, maybe adjusted for stage of competitors, may present that it’s a lot simpler for hitters to develop energy earlier of their skilled careers. I additionally fully ignored something apart from manufacturing numbers. A extra nuanced look may discover completely different outcomes for some physique varieties or swing shapes. Nootbaar, for instance, all the time appeared like he had extra energy in him; he’s 6-foot-3 and robust.

“You’ll be able to’t develop energy” is the mistaken takeaway right here; “it’s exhausting to develop energy” is nearer to the reality. That holds true whether or not you’re looking for fantasy breakouts or attempting to signal a free agent. In the event you’re on the lookout for a serious league metric to belief, Ninety fifth-percentile exit velocity is an effective guess. Extra so than another statistic I might provide you with, what you see is what you get, and what you see does an excellent job of telling you the way harmful a hitter will be when he’s at his greatest.