Going Deep: Jesus Take the Wheel

Nick Bucher diagnoses why Jesus Aguilar has struggled to live up to his breakout 2018 season, and explores if a rebound is possible over the final two months following his move to Tampa Bay.

Jesus Aguilar has been quite the enigma in 2019. After shocking the world in a breakout 2018 that saw him eclipse Eric Thames on the depth chart early on, Aguilar mashed his way to 35 homers and an OPS of .890 and was a huge part of an offense that propelled the Brewers all the way to the National League Championship Series. If he weren’t sharing a roster with Christian Yelich, he would have garnered some legitimate consideration for NL MVP. Even so, he did draw some down-ballot votes, was an All Star game nominee, and appeared to have broken out in ways that were sustainable. Aguilar wasn’t especially young, but did not turn 29 until midway through the 2019 season, so he figured to have some time remaining in his prime years for offensive performance.
Unfortunately, things couldn’t have gone much worse for Aguilar early on this season. Through July, he had compiled a meager .694 OPS and only eight homers across 262 plate appearances. Combined with his subpar defense at first base, the Brewers ultimately parted ways with Aguilar at the trade deadline, swapping him out for oft-injured starting pitcher Jake Faria with the Tampa Bay Rays. The Rays have a penchant for getting the most out of guys like Aguilar, and have built a reputation for being one of the “sharp” organizations, squeezing every bit of production more efficiently than most other teams. In recent years, they bought low on guys like Tommy Pham, CJ Cron, and Travis D’Arnaud just to name a few. Unquestionably, their plethora of versatile middle infielders and general utility types creates questions about Aguilar’s playing time, but there is absolutely a shot that the Rays help him unlock something the Brewers couldn’t see. The front office in Tampa Bay certainly has earned the benefit of the doubt, after all.

How Bad Has He Really Been?

Taking a look under the hood, there are some encouraging signs as to why the Rays would want to speculate on with Aguilar. Take a look at his Baseball Savant metrics for exit velocity, hard hit %, and xwOBA specifically:

Apart from being in the bottom 6% of the league in sprint speed, (which shouldn’t surprise anyone), Aguilar is still well above average at hitting the ball hard, and it does appear that he has had some poor luck in 2019. Aguilar’s spray chart in 2019 is also quite similar to what it was in 2018 with Milwaukee. He was pulling the ball about 4% less frequently, and had seen his hard contact rate decrease slightly from 44% down to just under 42%, but the most glaring difference was in his fly ball metrics.
In 2018 Aguilar had been hitting the ball in the air at a rate of .86 groundballs for each fly ball, and has seen that number climb over 1.0 in 2019. It’s not a huge difference, but Aguilar has a slightly lower line drive rate as well, so the combination of fewer fly balls, and fewer line drives hurts him. Additionally, his soft contact rate has slightly increased from 15.3% to right around 16.5% this year. These factors do help show why he has regressed, but Aguilar’s arguably most interesting statistical change has been in what has happened to his FB/HR rate. After hitting 23.8% of his fly balls over the fence in 2018, he’d seen it cut almost in half to just over 12% in 2019. Considering that Aguilar’s career rate is 20.1% even with this season, it seems likely that he will regress back toward that.

Let’s take a look at an absolute monster shot from the past week when Aguilar was facing a right-handed reliever late in a game against Miami:

Sure, it was poorly executed as this pitch did end up being a cookie over the middle. It’s noteworthy though that Aguilar did this against a pitch going 93 miles an hour too, but more on that in a moment…

Not So Fast…Ball…

His performance against specific pitches has fluctuated significantly. In fact, the majority of his total difference in performance has come against fastballs. According to Fangraphs’ Pitch Values, Aguilar grades right around 0.0 against fastballs in 2019. His numbers against secondary and off speed offerings have stayed around 2018 levels, with a small decrease in performance against sliders and split-fingered offerings offset by marginal improvement against curve balls, cutters, and change ups. This is not inspiring, but becomes even more difficult to fathom when put next to his performance against fastballs in 2018. Just a season ago, Aguilar graded out as being over 24 against the same classification. So while Aguilar has been roughly the same hitter against most pitches, his sudden and steep decrease in performance against fastballs has been the culprit. Take a look at how much it stands out on the chart below where highlighted:

Next let’s look at Aguilar’s heat maps against fastballs in more depth, he has had some interesting issues. Take a look at what Aguilar’s slugging percentage has been based on where he is seeing and making contact with fastballs so far in 2019:


And now take a look at how much different this same map looked in 2018 when Aguilar put a fastball in play:

It’s staggering how much more red he had last season. The easy takeaway is just that Aguilar has had much less luck on fastballs that he has put in play around the corners of the strike zone. In 2019, he has really only done damage against fastballs over the middle of the plate and/or up and away. How could he be doing so much more poorly against the same pitches he fared so well against a year earlier? Zooming out and taking a look at Aguilar’s batting profile on the whole, has he truly just become a worse hitter against the fastball over the past year?
It’s not quite that simple. When looking into expected statistics on Baseball Savant, Aguilar has been one of the more unlucky hitters all year. His expected batting average (xBA) of .253 is higher than his actual average at .236, and his expected slugging percentage (xSLG) of .466 is significantly worse than the .393 he has actually put up. Unsurprisingly, his xwOBA (the quality of contact in addition to strikeouts and walks) is also significantly better than what he has actually received. His .353 mark is notably better than the meager .316 wOBA he has accrued thus far. These aren’t guarantees, but over an extended period most batters do tend to have their future production normalize closer to their expected numbers than their actual outcomes. Aguilar is not absolved from blame, but the fact that a large chunk of his expected numbers aren’t out of whack is encouraging after seeing how different his actual performance has been. Presumably, the Rays know this too.

Where Do We Go From Here?

Since arriving in Tampa Bay, Aguilar has already begun to show some of the signs of turning his season around. Naturally, he’s been exposed to the magic in Tampa Bay and he’s shown in early action that he is worth being given semi-regular playing time with a homer highlighting a 6-for-15 start. In the incredibly small sample, he’s also walked three times, while only striking out once! It’s too early to make any kind of declaration, but there is a real shot that Aguilar could be a factor down the stretch now that he has a fresh start and may not have to play in the field as often with some chances to DH. With Nate Lowe back in Triple-A, Aguilar seems likely to split playing time at first base with Ji-Man Choi down the stretch, and if Aguilar performs, he could wind up with the job to himself. In the incredibly short sample so far with the Rays, they have played him against a right-handed pitchers already, including batting him third last week against Andrew Cashner of the Red Sox, and featuring him as the cleanup hitter against Toronto’s Tyler Thornton. The Rays have committed to giving him time at first base and designated hitter against lefties. If nothing else, Aguilar is certainly a situation worth monitoring over the final two months of 2019 if he is able to keep hitting the ball hard and plays regularly.

(Photo by Mark LoMoglio/Icon Sportswire)

Nick Bucher

Nick is a University of Maryland, Baltimore County (UMBC) alum, a lifelong Orioles fan, and a fan of all things baseball. He is smitten with fantasy baseball, both season-long and DFS, and will be elated when the O's win the 2029 World Series.

  • Avatar TheKraken says:

    Consistency is and always will be what matters the most. Analysis is mistakenly trending towards exit velocity which is actually a good indication of inconsistency. The things a player does to create ev are generally not good. Aguillar had a fluke 2018 and he had shown the ability to get hot before. Hes streaky. Very streaky. If you bet on him finding consistency in 2019 then you lost. I dont think there is too much to him beyond that. Mlb is full of quad a sluggers at the moment.

    • Avatar Nick Bucher says:

      Thanks for reading Kraken! I appreciate hearing your thought process, we will have to agree to disagree on Aguilar’s ability it sounds like, but I definitely enjoyed reading another opinion on him!

  • Avatar Rodger says:

    Nice piece, but dearth means scarcity. Maybe you meant plethora?

    • Avatar Nick Bucher says:

      Hi Roger, thanks for reading! You are absolutely correct, I had meant to say that there was “no dearth” and mis-represented. Thank you for letting me know so I could change it

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