Spin less?

Now, in an MLB game, we always see umpires check pitchers’ hands to see whether foreign substances are used. The MLB enforced foreign substance ban in June last year and since then, checking for foreign substances has been routinely. And, I’m just wondering whether this enforcement has truly changed something. A key thing came to my mind is spin rate, so I went to check on the statcast website to see the differences in spin rate.

From the 2021 opening day to June 20, 2021, average spin rate of 4-seam fastball was over 2300 rpm in the league. The enforcement was put into effect on June 21, 2021. After the enforcement, 4-seamers were, on average, spinning at a rate of 2248 rpm league wide last season. In the first half of the 2022 season, the league-average spin rate of 4-seam fastball was 2264 rpm.

In addition, before the rule enforcement, the average four-seamer spin rate of the Dodgers pitchers was over 2500 rpm. At the same time, the White Sox pitchers threw four-seam fastballs more than 4000 times and average spin rate was 2410 rpm. Also, the average 4-seamer spin rate of the Yankees pitchers was over 2400 rpm as well. In the meantime, the average spin rate from 10 other teams was over 2300 rpm. None of the 30 MLB teams had an average four-seamer spin rate lower than 2200 rpm.    After the rule enforcement, things were getting a bit more interesting. Average 4-seam fastball spin rate didn’t touch 2400 rpm from any of the 30 MLB teams. The Yankees pitchers’ four-seamers were spinning at a rate of 2358 rpm, on average. The average 4-seamer spin rate of the Dodgers pitchers was 2357 rpm. Furthermore, the average 4-seam fastball spin rate of the Padres and the White Sox each reached 2300 rpm. Nonetheless, from June 21, 2021 to the end of the 2021 season, there were 4 teams with average 4-seamer spin rate lower than 2200 rpm. Before the 2022 All-Star break, there were 7 teams with an average 4-seam fastball spin rate of 2300 rpm or higher. The Cincinnati Reds pitchers threw 4-seam fastballs more than 5000 times in the first half of the 2022 season and average spin rate of those 4-seamers was 2347 rpm. In the meantime, the Yankees pitchers’ 4-seamers spun at a rate of 2341 rpm, on average. But, looking at the average 4-seamer spin rate from the Mariners and the A’s, the number is lower than 2200 rpm. Of course, there are several reasons to explain the decrease of the average spin rate of four-seam fastball from each team. During the regular season, we frequently see that each team has some changes in rotation or in the bullpen. Perhaps, the baseballs used this season aren’t the same as those used last season? However, when we look at the stats league wide, it’s clear that the average spin rate of four-seam fastball didn’t touch 2300 rpm as we saw before the rule enforcement. It will be worth monitoring the number in the second half of this season to see whether there will be any huge differences.