Scott Paulus
The fact that the Brewers came within a single game of the World Series in 2018 can be at least partially credited to Jesus Aguilar, whose breakout season bumped Eric Thames from his spot in the starting lineup and helped power an offense that finished second in the National League in home runs and fourth in runs scored.
Aguilar was the first Brewer ever, and one of just 22 players in National League history, to hit 35 or more home runs in under 500 official at bats. As such, it’s easy to salivate over what he could do given a full season of everyday playing time in 2019. At least one projection system, however, isn’t as excited about the possibility.
Steamer, a widely-respected prediction model used at FanGraphs, among other places, has Aguilar projected for a major step back in 2019. Aguilar batted .274 with a .352 on-base percentage and .539 slugging in 2018. This projection has him dropping significantly in all three areas, hitting just .242 with a .317 on-base and .454 slugging in 2019. When combined with expected below-average defense, Aguilar’s value drops from 3.1 wins above replacement in 2018 to just 0.9 in the 2019 projections. That would also be a slight downgrade from Aguilar’s value in his partial MLB season in 2017.
The reasons for Steamer to project a major downturn for Aguilar are unclear: The system, originally developed by a high school science and statistics teacher in Brooklyn and his students, is proprietary, so it’s not possible to look into the data and see why Aguilar drops off. His age should not be a factor in any projected decline, however. Aguilar won’t turn 29 until June, and as such he should still be in the prime of his career for another year or two.
Stay on top of the news of the day
Subscribe to our free, daily e-newsletter to get Milwaukee's latest local news, restaurants, music, arts and entertainment and events delivered right to your inbox every weekday, plus a bonus Week in Review email on Saturdays.
Aguilar’s strikeout rate is also a bit of a concern, as more than 25% of his 2018 plate appearances ended with him being retired on strikes, down from over 30% in 2017. He’s not unique in being a star offensive player with a high propensity to swing and miss, however: In 2018 Cubs second baseman Javier Baez, Rockies shortstop Trevor Story, Yankees right fielder Aaron Judge and Diamondbacks (now Cardinals) first baseman Paul Goldschmidt all also had K rates equal to or higher than Aguilar’s. Those four players were still among the most valuable in baseball.
Aguilar’s projection also shows a significant decrease in his batting average on the balls he does put in play, falling from .315 over his first two seasons as a Brewer to .286 in 2019, well below the league average of .296. Dropping Aguilar’s BABIP by 29 points would cost him about 15 hits over the course of the season. It makes sense that a player like Aguilar won’t get extra hits by legging out infield singles, but he has a history of hitting the ball hard enough to make up for what he loses in speed and contact. Steamer does not give him the benefit of the doubt based on past performance here.
MLB’s StatCast data lends some credibility to that prediction, however, suggesting Aguilar hit his way into some lucky breaks in 2018. Given the quality and amount of contact he makes on his swings, Baseball Savant estimates that Aguilar could have been expected to post a .255 batting average and .491 slugging in 2018, down 19 and 48 points from his actual numbers, respectively. That doesn’t cover the full gap between his 2018 numbers and Steamer’s projections for 2019, but it does narrow it a bit.
It’s also worth noting that Aguilar’s numbers dipped significantly following the All Star break last season. In his final 62 regular season appearances in 2018 Aguilar posted a .760 on-base plus slugging, down from .995 before the break. He still connected for 11 home runs over that time, but the pace of his offensive contributions slowed significantly, raising some questions about whether his first half was an actual breakout or just a prolonged hot streak.
It’s possible the Brewers are also acknowledging a wide array of possible 2019 outcomes for Aguilar by holding onto Eric Thames, who lost playing time to Aguilar in 2018 and doesn’t have a clear path to consistent at bats in 2019 unless Aguilar falters or gets injured. Steamer projects Thames for significantly less playing time (200 plate appearances) but his expected batting line (.235 average, .329 on-base and .459 slugging) isn’t much different from Aguilar’s.
At the end of the day most projection models are just a well-educated guess based on past outcomes, and there are certainly plenty of cases where they’ve been incorrect. Steamer correctly predicted Chase Anderson’s step back in 2018, however, and now they have the same expectation for Jesus Aguilar in 2019.
