These Aren’t the Hits MLB Wanted

There have been some scary moments in the first few weeks of the 2021 major league season. On April 28, Phillies Manager Joe Girardi was ejected after both Didi Gregorius and Bryce Harper were hit by pitches while they were playing the Cardinals. Harper’s incident was particularly scary as he was hit in the face with a 97 mph fastball. On April 5, Cubs catcher Willson Contreras was plunked by a 93 mph fastball to the helmet. Two days later Reds rookie Jonathan India had a similar moment after a fastball ricocheted off his helmet.

It’s not your imagination: batters are being hit by wayward pitches at a record clip. Ken Rosenthal of The Athletic made note of the trend this morning. Baseball Prospectus’ Rob Mains recently published an excellent breakdown of this year’s record-setting pace for hit batsmen. I was particularly taken aback by this chart showing that prior to 2018, no season in baseball history had a hit batsman in more than 1 in 103 plate appearances:

Mains continues:

There was one batter hit per 96 plate appearances in 2018, a new record. It fell further, to 94, in 2019. Then all the way to 81 in last year’s short, weird season.

This year? Through Tuesday night’s games, it’s down to 74.5. Batters are being hit thirty-eight percent more frequently than in 1901. There are just over eight hit batters for every five just a decade ago. We’re averaging 0.997 hit batters per game in 2021, a single HBP shy of one per game—a level the sport’s never approached. Batters so far have a .309 on-base percentage. Hit batters account for thirteen points of that figure. Ten years ago, there were only eight points of hit batters in MLB’s .321 OBP.

I wanted to take a look at possible reasons the HBP rate is at record levels so far in 2021, but first we need to be clear about which parts of this trend are continuations from previous seasons and which parts are actually new. In 2019, Devan Fink demonstrated that the HBP rate per plate appearance was approaching the highest levels seen since the early 1900s. He looked at increased velocity and reliever usage to demonstrate that while a pitches’ speed didn’t necessarily mean a pitcher had worse command, relievers had a larger share of HBP than their starting counterparts.

It’s still true that relievers are responsible for more hit by pitch events than their starting counterparts. I looked at reliever/starter splits and HBP rates through May 4th. While the rates of HBP are climbing for both groups, they are rising faster for relievers, as you can see below:

What’s interesting here is that the increased number of hit by pitch events isn’t merely a function of relievers being used more frequently. As you can see above, the proportion of total batters faced by starting pitchers has actually increased by about 2.5% between 2020 and ’21 – yet HBP rates continued to go up. So we are left with a situation where HBP rates are increasing for starters and relievers and the rates of HBP are increasing more rapidly for relievers.

The Athletic’s Eno Sarris has often cited Command+, a STATS metric for a pitcher’s ability to control pitch location, in his work, noting that relievers generally (and unsurprisingly) have lower Command+ metrics than starters. You can get a good feel for how starters and relievers differ in Command+ from this intro to Sarris’ starting pitcher rankings in 2021:

Stuff metrics are exciting, but if a pitcher doesn’t have a certain level of command, they’ll end up in the bullpen. The very bottom of the Command+ leaderboard is 90 percent relievers (and also Joey Lucchesi), which should tell you something. The very bottom of the Stuff list? A bunch of position players, Jason Vargas… and Joey Lucchesi. Man.

It makes intuitive sense that pitchers throwing harder with worse Command+ would miss their spots more frequently. If those spots are inside, I’d expect that to translate to more hit batters. To determine if pitchers are throwing inside more, I pulled the attack zones for every pitch in the Statcast era (2017-2021) by season. Statcast divides possible pitch locations into four sections (heart, shadow, chase, and waste), each with specific areas to pinpoint pitch location and compare it over time. And then I got a bit stuck, because, as Chet Gutwein noted last week, pitchers aren’t targeting the chase and waste zones more. If anything, they are targeting the heart of the zone more, specifically the top of the heart and shadow zones.

So we need an explanation for the increase in the HBP rate that addresses both starters and relievers, where relievers have a more pronounced problem despite both starters and relievers attacking he heart of the strike zone more. That left me with two possible explanations, both of which deserve further investigation. My first inclination was to look at MLB’s crackdown on sticky substances and the ball itself (or perhaps some combination of the two). After all, while some pitchers may be using substances to get an edge overall, we also know from previous research that the dry weather that can accompany cold days can make it hard to get a grip on the ball. We also know that MLB changed the baseball this season, deadening it slightly in an attempt to dampen home run rates. However, those changes seemed to have unintended consequences as well. Ben Lindbergh and Rob Arthur analyzed a number of those unintended consequences after Spring Training for The Ringer and found the ball was moving more on some pitches, which seems relevant to the rise in HBP incidents:

The higher-drag balls also seem to move more: Fastballs gain an extra 0.45 inches of vertical movement, and curveballs add 0.3 inches, relative to the lower-drag balls. In possibly related news, the higher-drag balls have a higher whiff-per-swing rate, by almost 3 percentage points. None of these findings conflicts with what Snell and Cole said: A difference in seams could account for improved grips, greater comfort, and more movement, as well as elevated drag, which could cause balls to carry less but possibly still fly farther if they’re leaping off the bat at higher speeds.

However, Arthur subsequently looked at HBP incidents for Baseball Prospectus and found that pitch location is relatively unchanged from 2017-21 but the same pitches are resulting in more hit batsmen, which leads to a curious culprit: hitters who are either unable to get out of the way of pitches due to advances in techniques like tunneling or simply a willingness to take one for the team to get on base:

It’s worth noting that the movement on these specific inside pitches hasn’t changed in any discernible, consistent fashion. They aren’t suddenly breaking in on hitters much more than they used to; they aren’t moving much faster than they used to. There’s no particular reason to believe they are harder to dodge or placed further inside, on average. It comes down to this: the pitches that used to almost never hit right-handed hitters are suddenly doing so almost twice as often.

There are possibly innocent explanations for this that can’t be ruled out. Maybe hitters have become so befuddled by their mound counterparts’ overwhelming arsenals (albeit, not the specific pitches that hit them) that they can’t react in time to get out of the way. Maybe pitchers are more deceptive now. Maybe pitch tunneling, which has been on the rise for years, has succeeded in forcing hitters to decide what to do a little later, taking away crucial fractions of a second for ducking. But there’s no sign that this plunking spike is a pitcher-driven effect: After accounting for the speed, break, and location of pitches, the model shows that hurlers have almost no additional impact on the probability of a HBP.

So I took a look at the hitters who had the highest percentage of HBP events per plate appearance from 2017 to 2021. To keep weather conditions as static as possible, I only compared Mar/Apr data for the last five seasons and then sorted it by the percentage of HBP incidents that occurred per plate appearance to see if there were any patterns in that data:

Now we are getting somewhere. There are certain teams that jump out in this list, most notably the Cubs, Dodgers and Reds, whose players make up 40% of the players who were HBP in at least 5% of their April plate appearances. To be clear, this doesn’t mean those teams have an organizational philosophy to get hit with pitches; it could be more about how teams game plan for those hitters. For example, there is evidence that teams have strategically thrown up and in against the Cubs to keep them from doing damage as down ball hitters. The solution to such an approach is even less clear – punishing a team for getting hit as a result of game planning meant to limit their offense would only further serve to constrain offense in an environment already characterized by a lack of hits and record number of strikeouts.

There has been a lot of consternation over the lack of non-home run hits in baseball over the last few seasons. Unfortunately for MLB, it appears that a combination of increased reliever usage combined with teams developing game plans for limiting home runs may have inadvertently contributed to a record spike in hit batsmen.