The science of the "Say Hey Kid"

What made Willie Mays different

I read a lot of obituaries about the great Willie Mays over the past week. And I was struck by something that kept popping up again and again when discussing Mays’s unique and profound greatness.

A lot of people talked about his hands.

This, from Tom Boswell in The Washington Post: “Mays’s fingers were like cigars. ‘He has Wes Unseld’s hands,’ I thought. Because Unseld is 6-foot-7 and 245 pounds in the NBA record book and Mays, on my 1957 Topps card of him, is listed as 5-10, I suppose this is impossible. But myths, and memories, have their prerogatives.”

From David Schoenfeld in ESPN: He had “huge hands that gripped the bat like a toothpick.”

From the NYT obit: “His frame seemed ordinary at first glance — 5 feet 11 inches and 180 pounds or so — but he had unusually large hands.”

From Dusty Baker: “[Mays once] showed me his hands. The muscle between his thumb and his forefinger looked like a golf ball in there.”

And Bobby Valentine: “Willie's hand would engulf your hand. It gulped it up."

Get the picture? If not, well, here’s a picture:

A scene reminiscent of the “Manhands” episode on Seinfeld

That’s Mays shaking hands with Ty Cobb in 1958, well before photoshop or Midjourney was invented.

How about this one?

That’s a lot of baseballs fitting comfortably within a single grip.

So let’s consider — did Willie’s hand size actually matter to his greatness?

Get a grip

The NBA and NFL draft combines have for years measured hand sizes of incoming prospects as a [very] crude means of gauging a player’s ball control. Hand sizes are discussed especially frequently among quarterbacks — I remember Michael Vick’s relatively stubby paws being a topic whenever he fumbled or threw an errant pass. The largest hands among active QBs belong to Jordan Love of the Packers (10.5 inches), but there about a dozen others within a few hairs of that mark. Joe Burrow (9 inches) has some of the smallest hands in the league. He’s still pretty good.

Mays’s hands are a different matter, because they perform a different task. For a baseball hitter (I’m focusing on hitting today), the hands are used for one thing: gripping the bat. In clinical terms, this is known as the “power grip.” (Gripping a ball is called a “precision grip.”). And it’s easy to surmise that a handshake is a good indicator of how somebody might grip and swing a bat. But that’s not really how we swing a bat at all.

Performance coach Chris Yeager says that professional baseball hitters actually don’t “swing” a bat. They “throw” a barrel.

In his view, the hands at contact are nonessential: One could completely lose his handle on the bat upon contact and it would not change the outcome of the hit. Indeed, just look at some of Ichiro Suzuki’s hitting highlights to see how this might actually bear out.

Studies on swing mechanics basically confirm this notion. Force-time signatures during a batting swing (as well as a golf swing, hockey slapshot, and tennis forehand) tend to show some commonalities. One is that the force of grip is low during the backswing and then ramps up dramatically during the acceleration/downswing phase. Grip force tightens right before impact but then reduces at impact. The peak of grip force doesn’t usually occur until after the ball has already left the bat. This is probably because the hands reflexively tighten so that the bat doesn’t fly out of the hitter’s hands.

The amount of force used to grip a bat or club is inversely proportional to wrist range of motion. In other words, as I move my wrist joints more, my grip force goes down. Why is that important to know? It implies that the timing of applied force during a swinging motion might be more important than the amount of force itself.

The force be with you

Yet a lot of studies have looked at grip strength and its relationship to hitting. One of them just published earlier this month.

It was sent to me by my friend Greg Appelbaum at the University of California-San Diego, who co-authored the study along with Jordan Kohn and a few others.

They examined Trackman data from more than 74,000 swings during the 2022 and 2023 seasons in the Appalachian League, a high-level collegiate baseball league. Each of the 189 players surveyed had completed a performance assessment via USA Baseball’s Prospect Development Pipeline, a sort of scouting combine for baseball prospects.

The PDP conducts a whole battery of physical tests, assessing everything from vision to cognitive processing. But, Appelbaum told me, they decided to settle on three measures in particular: 30-yard sprint speed, a type of vertical jump test called “countermovement jumping ability”, and grip strength. With the scores on these three tests, they could look at all 74,000 swings to find links between test results and hitting outcomes.

Overall, the researchers found that the measures captured in the PDP assessment (plus height and weight) accounted for 50 to 55 percent of the variance in “hard hits” (in-play batted balls with an exit velocity above 95 mph) during the two seasons that were measured. That’s a very strong outcome. “I think it is pretty darn impressive that we can predict >50% of the variance in hard hit percentage from real games,” Appelbaum says.

As for grip strength, it came in fourth among contributors to “hard hits,” behind only height, weight, and countermovement jumping ability (an assessment of lower extremity strength). It was more predictive than age, sprinting speed, vertical hang time, and position. But it’s probably important not to get carried away: If you want to predict how hard a prospect is going to hit the ball, best to start at the legs.

Long drives

Other studies have poured water on suggestions that grip strength has anything to do with bat speed velocity at all. A 1997 study on expert softball hitters found that the mean grip strength in players was significantly stronger than non-players, but this isn’t a determinant of batting success. It just means that they regularly got resistance training from swinging a bat.

A 2004 study by Shawn Hughes, et al., put baseball players on a training regiment for 6 weeks to strengthen their grip to see if it would improve bat speed. At the end of the program, there was no difference between the grip trainees and controls. Hughes concludes that “grip strength and bat velocity are not significantly related.”

A swing, like most skilled movements, is at its most efficient when it is produced via a solid kinetic chain. Kinetic refers to energy, in this case derived from the ground when you plant your feet to begin the swing motion. The energy from there travels upward — in baseball hitting, usually the four prominent segments of the kinetic sequence are the pelvis, truck, forearms, and hands. Each segment accelerates and then decelerates sequentially — the hands are the last “link” in the chain receiving and then distributing that energy through the swing. It would make sense, from this standpoint, that strong hands would be less important to a swing sequence than the legs, trunk, or forearm that are responsible for the earlier sequential power generation.

I think it’s interesting, though, that golf studies have found the opposite.

Several papers (from Torres-Rhonda, 2011; Cummings, 2018) have drawn links between grip strength and faster clubhead speed, contributing to longer drives. And maybe that can be chalked up to the differences between the rotational path of a golf swing vs. the more parallel plane of a baseball swing.

However, a review by William Sheehan, Rob Bower, and Mark Watsford from Sydney, Australia, in 2019 offers a different explanation of the influence of grip strength on golf swings: It’s not really about the grip at all.

During the acceleration (downswing) phase of a tee shot, higher levels of muscle activation have been recorded in the flexor carpi ulnaris. That’s a forearm muscle that begins at the elbow … and ends right at the base of the pinkie finger. “Increased grip strength,” wrote Sheehan, et al., “may positively influence” the activation of this flexor “that occurs just before impact, which contributes to high endpoint velocity.”

Bingo.

Grip strength seems to matter, but not for the hands. For the forearm. That’s where the bulk of the acceleration appears to be generated. But it doesn’t happen without a strong grip.

I do suspect the other studies were probably correct in that doing hand-strengthening exercises at the expense of something else probably is a waste of time. Can’t imagine Mays bolstered his mitts with finger exercises; his hands probably grew, along with his legs and forearms, playing various sports and doing other physical activities from a young age.

Links

The cooling technology at the Summer Games … Could ADHD be a superpower for some athletes? … AI can read athletes’ body language … ‘Malevolent’ traits may be key to athletic success … Video games and neural plasticity: StarCraft II expertise linked to enhanced brain connectivity … Performance data has finally come to sailing … Why does Bryson DeChambeau float his golf balls in salt water? … Blood sugar goes low and stays low with exercise at this time of day … How science built the best shooter in the NBA draft … The new calculus of summer workouts … What works for golf works for life … Supershoes are reshaping distance running … AI batting buddy

References

Cronin, John, et al. "A brief review of handgrip strength and sport performance." The Journal of Strength & Conditioning Research 31.11 (2017): 3187-3217.

Hughes, Shawn S., Brian C. Lyons, and Jerry J. Mayo. "Effect of grip strength and grip strengthening exercises on instantaneous bat velocity of collegiate baseball players." The Journal of Strength & Conditioning Research 18.2 (2004): 298-301.

Kohn, Jordan N., et al. "Strength, speed, and anthropometric predictors of in-game batting performance in baseball." Journal of Sports Sciences (2024): 1-8.

Sheehan, William B., Rob G. Bower, and Mark L. Watsford. "Physical determinants of golf swing performance: A review." The Journal of Strength & Conditioning Research 36.1 (2022): 289-297.