Injury and Fatigue
The primary reason for Moustakas’ recent struggles in the home run department likely comes down to his health.
Coming off a devastating knee injury in 2016, Moustakas was always likely to fatigue more down the stretch than his teammates. His participation in the Home Run Derby and the All-Star Game kept him from getting what could have been vital rest over the All-Star break.
Even still, Moustakas increased his home run total from 25 at the break to 30 by the end of July. The third baseman added another five homers in the first half of August. The last of those came on Aug. 15 at Oakland.
Moustakas did not hit another home run in August. A knee injury that appeared to be sustained on Aug. 26 in Cleveland seemed to slow him down considerably for the final few days of the month. However, Moustakas went deep in a key series-opener with Minnesota on Sept. 1. That blast tied him with Balboni for the single-season mark.
He hasn’t gone deep since.
The knee has still clearly been bothering Moustakas in September. He has sat out a couple of games to try to rest it. He’s also been replaced early on five different occasions—although those had more to do with blowouts than anything else.
It’s worth wondering, if Moustakas had already set the record—say he hit a second homer in that Sept. 1 game—would manager Ned Yost have given him more rest the past few weeks. In turn, that additional rest might have allowed the knee to fully heal and have Moustakas as close to 100 percent as possible for the Kansas City Royals’ stretch run.
Regardless, the lack of home runs can also be partially attributed to at least one other reason.