Here’s my final prediction for the number of home runs that Giancarlo Stanton will hit in the 2017 season. I’ve described my methodology in previous posts. Essentially, I use the home run data for all players to learn about Stanton’s probability of hitting a home run in a single at-bat. Then I simulate predictions from this model to learn about the probability that he hits Y home runs in the remaining games. All of the R code for collecting the data, doing the estimation and simulating the predictions is in my BApredict package.
Currently (through games of Wednesday) Stanton has hit 56 home runs in 555 at-bats and his team has 10 games to play. Here is my graph of the probability that he will hit Y home runs in the remainder of the season.
Looking at this, he is most likely to hit 3 more home runs (total of 56 + 3 = 59) and there is a 92 percent chance that he will hit between 1 (total of 56 + 1 = 57) and 6 (total of 56 + 6 = 62). The chance that Stanton breaks Maris’ record of 61 home runs is only about 10%. But of course the probability that Stanton breaks the record can change as these final games play out.