MLB offense is atypically cooling off this August, especially in the AL
Something unusual is happening in baseball this August: Offense is cooling just when it's usually peaking.
Hitters' OPS this month, .702, is the lowest it's been since 2014, and down 30 points from the same month last year. This is counterintuitive during the time of the season when the warmer weather would favor ball flight.
The numbers are down slightly in the NL, but Cyril Morong, a retired economics professor and sabermetrician, noted on Twitter that OPS is down significantly in the AL. Entering play Thursday, the August OPS in the AL was .679, a drop of 57 points over last season.
Other than the 2014 dip, August OPS numbers hadn't been under .700 in the AL since 1976. The AL's July OPS (.719) was down from last year (.726) but not as significantly.
This is an unusual decline. Given how baseball has handled its game ball in recent years, moving between juiced balls and less lively versions - and even using both last season without telling anyone - that kind of change can raise suspicion. Moreover, the spin rate of pitches is inching up in a curious way even after MLB got serious about enforcing its rulebook ban on sticky substances. So what's going on?
Much of the American League's drop in OPS results from a bunch of missing home runs. Through Wednesday's games, AL hitters had connected on only 290 home runs in August. They would have to hit another 241 homers in the final seven days of the month to reach last August's total of 531.
The home run to fly ball rate is down to 9.3% in August in the AL, lower than the rate in April (10%) when teams based in the Midwest and Northeast are often playing in much chillier conditions. In the AL, HR/FB rates were 11.7% in July and 11.6% in June. The AL full-season rate is 11.3%.
The August HR/FB rate in the NL is down from 13% in June to 11.8% this month, though slightly up from July (11.4%). But this month's rate is below every August rate since 2014 in the NL, which is also true of the AL.
In the AL, hitters' average exit velocity (88.4 mph in August vs. 88.5 mph in July) hasn't significantly changed, although the barrel rate - a metric that combines launch angle and exit velocity to define optimum contact - is down slightly (6.9% in August vs. 7.3% in July). But those don't seem to be enough to explain why home runs are down this August when they are normally at seasonal peaks.
What is happening on the mound that might be impacting August's offense?
The spin rate on four-seam fastballs is down this August compared to the same period (Aug. 1-22) of 2020, but up from last season, after the league began cracking down on sticky stuff in June.
The average four-seam spin rate sits at 2,293 rotations per minute this year compared to 2,244 in the same period last year and 2,304 in August 2020. A higher spin rate on this pitch allows it to use the Magnus effect of airflow over the baseball to more effectively work against gravity.
When adjusting for velocity - spin increases with velocity - this year's August period is also lower than 2020, thought to be a peak year for sticky stuff, but greater than last year, when policing efforts began. Why does that matter?
Because spin rate has also inched up since the season began.
The average rpm per mph was 24.07 in April but rose to 24.4 this month. That didn't happen in 2019, the last full season without any sticky-stuff policing efforts. April rpm/mph in 2019 (24.58) was actually slightly greater than in August (24.51).
Perhaps pitchers have found a new way to improve spin that is eluding umpires' mid-inning hand checks. MLB did not respond to a request from theScore to discuss how it is evaluating the hand-check policy.
Only four American League teams (the Astros, Orioles, Rangers, and White Sox) have an August OPS above the season-long MLB OPS of .699. Only five teams had OPS marks below .699 in August 2021.
There are perhaps a number of culprits behind the August OPS outage, but whatever the reasons, it will be interesting to see if it continues over the season's final, pivotal weeks of play.
Travis Sawchik is theScore's senior baseball writer.