MLB Should Consider Lowering Mound, Even Though It Probably Won’t Boost Offense
This began as a brief commentary on one of the many rules changes being proposed by Major League Baseball and the players union, but quickly grew beyond the narrow confines of that format. In addition to various and sundry limitations on pitcher usage and roster spots, Jayson Stark of The Athletic detailed the potential of forming a joint committee to study whether moving back and/or lowering the mound ($) would aid hitters.
While it sounds like heresy to suggest a change to the distance of 60 feet, 6 inches we all know so well, the shift might be very minor. I can imagine Twitter having a lot of fun with a move to 60 feet, 9 inches. Besides, any change is likely to be much less extreme than the move from 50 feet back in 1893.
So moving the mound farther from the plate, even by a few inches, has emerged as one possible solution to help hitters catch up with extreme velocity and cut down on strikeouts. Sources said MLB proposed forming a committee, made up of two MLB appointees and two union appointees, to study that option. While the union hasn’t yet agreed, indications are that it is at least receptive to the idea.
I want to circle back to the distance thing, but let’s turn our attention for now to the other aspects of the proposal.
There’s a much more recent precedent for lowering the mound, which went from 15 inches to 10 following the 1968 season in which seven pitchers posted ERAs under 2.00. That group was led by Bob Gibson‘s other-worldly 1.12 over nearly 305 innings for St. Louis. As further proof that it was a pretty weak year for offense, Carl Yastrzemski won the batting title with a .301 average. But it’s not as though the mound was the only change made to swing the balance of power back to hitters.
In addition to cracking down on doctored baseballs, the league redefined the strike zone from its previous knees-to-shoulders limits to the armpits and the top of the knees. The bottom of the zone was eventually expanded in 1996 to the hollow beneath the kneecap, but umpires have routinely given a lot of leeway even lower.
A 2014 article by Jon Roegele in The Hardball Times found that the low end of the strike zone had dropped three inches in total — from 21 inches off the ground to 18 — over the nine seasons between 2008 and 2014. That doesn’t seem like too big a deal, right? After all, we’re not even talking about the diameter of a baseball. But when that relatively tiny space encroaches upon an area hitters already find inhospitable, the differences become noticeable.
The expanded zone resulted in a 43 percent drop in expected runs during the 2014 season as compared to 2008 over virtually the same number of total pitches (129,593 to 125,599 — a 3 percent difference). Another chart available in Roegele’s article shows that hitters actually started to swing at a higher percentage of lower pitches as well. More pitches thrown lower and more swings at those pitches means weaker offensive performance.
Other factors contributed to the decreases in run-scoring over the period in question, but the deleterious effects of an expanded strike zone can’t be denied. Manfred has talked about tightening the zone for a while MLB had proposed moving the bottom end back to the top of the knees two years ago, so there’s already momentum there. Raising the zone will almost certainly make more of a difference than lowering the mound, which may not have much of an impact at all.
The Journal of Science and Medicine in Sport recently published a study by a team of experts* titled, “The influence of mound height on baseball movement and pitching biomechanics.” After measuring the results of fastballs and curveballs thrown from four different mound heights — 15 cm (~6 in), 20 cm (~8 in), 25 cm (~10), 30 cm (12 in) — in a randomized order, researchers concluded that there were “no significant differences observed for ball movement.”
So while a change to the height of the mound would alter the downward plane of pitchers’ offerings, it isn’t likely to promote offense in any meaningful way. There could, however, be an ancillary benefit for pitchers that would be of significant interest to all parties involved.
There were no significant kinetic differences for curveballs, but five kinetic parameters (elbow varus torque, elbow flexion torque, elbow proximal force, shoulder internal rotation torque, and shoulder anterior force) varied with mound height for fastballs,” the report read. “In general, fastball kinetics were 1%–2% less from the lowered (15 cm, 20 cm) mounds than from the standard (25 cm) or raised (30 cm) mounds.
If that strikes you as a bit confusing, we can distill it to say that pitching from a lower mound “may slightly reduce shoulder and elbow kinetics, possibly reducing the risk of injury.” That’s far from a definitive statement and we’re looking at a very slight decrease percentage-wise, but even the most seemingly insignificant statistical differences can shine through over hundreds of thousands of pitches.
And if rules are implemented to limit teams to 12 pitchers, then to mandate that those pitchers face a minimum of three batters per appearance, individual workloads will increase. I’m not certain whether or how directly injury risk correlates to that increase, but it seems reasonable to assume there’d be some sort of relationship.
Is it weird to think MLB would actually be less willing to consider lowering the mound if the results are more about injury prevention than run production? Then again, the league is trying to generate more interest in its product. And one of the easiest ways to put the best possible product on the field is to take every possible measure to keep the best players on the field. So just drop the mound a little bit and make sure the strike zone is being called as accurately as possible.
Okay, so now we come back to the idea of increasing the distance from the mound to the plate. It’s a novel concept, to be sure, and one that might indeed help to offset rising velocity numbers. But I’m wondering whether the impact of gravity over the added distance, while nominal, would combine with a higher zone to help hitters too much. I guess that’s why they’ve got a committee.
As with so many other changes, it’s hard to know exactly what kind of an impact any adjustments to the mound or the zone will have until they’re put into live gameplay on a large scale. So maybe MLB should just implement silly contrivances like runners on second in extra innings so the other changes don’t seem so bad.
*Alek Diffendaffer, Jonathan S. Slowik, Nicholas J. Lo, Monika Drogosz, and Glenn Fleisig of the American Sports Medicine Institute