There are few milestones in baseball that inspire more excitement than the possibility of a player hitting 60 home runs in a season. There are just eight of those campaigns on the books — Babe Ruth (60 in 1927), Roger Maris (61 in 1961), Mark McGwire (70 in 1998, 65 in 1999), Sammy Sosa (66 in 1998, 63 in 1999 and 64 in 2001) and Barry Bonds (major league record 73 in 2001) — and none in the past 18 years. Giancarlo Stanton hit 59 home runs in 2017, the closest anyone has come to the 60-home-run mark since the league instituted mandatory drug testing in 2006.
Three players this year have a chance to end the drought. Christian Yelich (Milwaukee Brewers), Cody Bellinger (Los Angeles Dodgers) and Pete Alonso (New York Mets) each hit 30 or more home runs before the All-Star break, putting Yelich and Bellinger on pace for 57 home runs and Alonso on pace for 53 home runs this season. However, those estimates, especially for Bellinger, could be on the low side for several reasons.
Home runs are being hit at a record rate this season with the possibility of smashing the previous record set in 2017 by as many as 700 home runs. Bellinger also gets the benefit of playing 36 of his team’s remaining 66 games against opponents who give up an above-average rate of home runs per plate appearance. Yelich (27 of 67 games remaining) and Alonso (24 of 69 games remaining) don’t get nearly the same benefit from the schedule. Dodger Stadium is also the 10th best hitter park this season in terms of home run park factor. Miller Park (14th) is average and Citi Field (18th) is below average.
Balls are also traveling further than ever before, perhaps due to what a committee of scientists commissioned by MLB called “a change in the aerodynamic properties of the baseball.” Fly balls are traveling 323 feet, on average, this season, the furthest since Statcast started collecting data in 2015. More fly balls are converted into home runs, too, this season.
Add in warmer weather, which typically ushers in an increased home-run rate, and you have all the ingredients necessary for a magical season. For example, from 2006 to 2018, 2.6 of plate appearances in March and April resulted in a home run. This April we saw home runs in 3.4 percent of plate appearances. From 2006 to 2018 we saw 2.7 percent of plate appearances in May go deep. This May that rose to 3.6percent with even higher rates in June and July.
Based on their ratio of home runs to plate appearances in the first half of the season and the estimated plate appearances remaining in 2019, Bellinger and Yelich each have at least an 88 percent chance of hitting 50 or more home runs this year.