In 1930 Hack Wilson hit a MLB record 191 RBI in a single season. Lou Gehrig had the AL record, 185, the following year for the Yankees. Since then nobody has come closer than Manny Ramirez with 165 in 1999.
Obviously, Wilson had a great year at the plate—one of the best ever—hitting .356, OPS 1.177, with 56 homers. However, we all know RBI also requires batters getting on base ahead of the hitter. Some have posited that the record in unbreakable. Is it? What would it take?
Wilson hit cleanup in all 155 games he played in 1930, so let’s use that as an assumption. The Boston Red Sox had 3 batters in the top 15 in MLB in OBP: Mookie Betts (.391), Xander Bogaerts (.384), and JD Martinez (.383). Together they reached base 796 times last year. They also all drove themselves in a lot with home runs (98 between them). That leaves 698 base runners. The exercise requires assuming they bat 1-3 every game, and don’t score any of those 698 times they’re on base before the cleanup batter comes up. There also has to be a good hitter to be that cleanup batter. The Red Sox’ Rafael Devers could be that candidate for 2019. He hit .311 with 32 home runs. His theoretical max RBI would be .311 x 698 = 217 plus the 32 homers, or 249. To get to 191, he would have had to drive in 77% of the theoretical max. Three fourths of the time a guy on first has to score on a hit—that doesn’t happen that often. The top 3 in the lineup do drive each other in and don’t hit only solo homers, too.
Is 191 impossible? No, but I’d call it very unlikely, certainly in today’s game. To do it, the opportunities have to be maximized—3 hitters at the top of the lineup who get on base a lot, hit lots of doubles and triples to get in scoring position (or singles with stolen bases) but not a lot of homers and not a lot of driving each other in ahead of a big bat in the cleanup position consistently driving them in.