With baseball now in the Juiced Ball Era, it seems that there are a dozen new players becoming superstars every season. Players like Christian Yelich, Eugenio Suarez, and Marcus Semien were solid players in their first few seasons but have since turned into MVP-caliber stars. On the other hand, increasing home run rates have made homers a dime a dozen, leading way to three-true-outcomes players like Jorge Soler, Franmil Reyes, and Hunter Renfroe. In this strange season, one player stood out above the rest as the strangest, most unexpected breakout of the season: Ketel Marte.
Throughout the first four seasons of his career, Marte was a solid defender, but a liability on offense. Despite putting up a 112 wRC+ in 57 games his rookie season, he followed that up with a 67 wRC+ and -0.4 fWAR in 2016 with the Mariners and an 89 wRC+ in 2017 after being traded to the Diamondbacks. He bounced back in 2018 with a 106 wRC+ in 2018, to go along with a career-high 14 home runs. At this point, Marte looked to be, at best, a league-average hitter with above-average defense. Of course, there’d be no need for this article if something drastic didn’t happen.
Let’s start with the most obvious improvement: the home runs. Coming into 2019, Marte hit 22 home runs in 1,548 career PA. This season, he hit 32 in 628 PA. Now, some of that can be attributed to the juiced ball, but it’s hard to believe that’s the sole reason his home run total more than doubled in less than half as many plate appearances. To get to the bottom of it, we’ll have to dig deeper into the numbers. According to Statcast, while Marte’s average exit velocity only increased from 88.5 MPH to 89.8 MPH over the last season, his average launch angle jumped from 5.7 to 11.5 degrees. Believe it or not, hitting balls higher in the air tends to lead to more home runs, especially if you hit them to the pull field.
As you can see in the charts above, Marte hit only home run last season to the opposite field, regardless of which side of the plate he hit from. According to Fangraphs, Marte pulled the ball 43.7% of the time in 2019, up from 36.7% in 2018. The combination of pulling the ball in the air more often and hitting the ball a little harder, as well as the juiced ball, provides a reasonable explanation for his huge increase in power.
The other major difference in Ketel Marte’s season was the massive increase in batting average. Say what you will about batting average being a useful statistic nowadays, but when the change is this massive, you tend to take notice. Coming into this season, Marte was a career .263 hitter, with a career-high mark of .283 set in his rookie season. In 2019, Ketel Marte hit .329, finishing 0.0006 points behind Christian Yelich for the NL lead. Digging a bit deeper, Marte’s xBA, which measures the expected batting average of a ball in play based on launch angle and exit velocity, is .295, good for 12th among qualified hitters. However, the 0.034 difference between his actual batting average and his expected batting average was the 7th highest difference among qualified hitters, showing that he may have gotten a bit lucky this season.
So where does this leave Ketel Marte? Is he going to continue to play like a superstar? Is he going to regress à la 2017 Marwin Gonzalez? More than likely, he’ll probably end up somewhere in the middle. Marte won’t turn 27 until next October, meaning he should be just reaching his prime and should continue hitting like a superstar. However, most of his numbers point to him regressing a bit, meaning he’ll still play well, but just not MVP-candidate well. As long as the juiced ball is in play, however, expect surprising breakouts like Marte to continue to occur.