At the end of April, it appeared the Brewers had found a franchise player in Eric Thames. Bolstered by a monster stretch against Cincinnati, Thames set the MLB on fire with his power and patience at the plate. Through the first month of the season, Thames set a torrid MVP pace that would be difficult to maintain, hitting .345/.466/.810 with 11 HR and an otherworldly 17.5% walk rate.
What made Thames’ April even more impressive is that it looked to be the product of skill alone. His .360 BABIP was not severely bloated when compared to hitters with similar profiles, and he was hitting the ball “hard” nearly 50% of the time.
Despite this, the signs for regression were ever-present, including: a) Thames pulled the ball 59% of the time, tops in the majors, making his extremely susceptible to defensive shifts; b) Thames body, especially his legs, was not responding well to the rigors of the non-stop MLB schedule; and c) Thames sported an unsustainable 45.8% HR/FB rate (home run to fly ball rate) that drove his April success.
While regression to the mean seemed likely, the magnitude to which it has played out was beyond anyone’s expectations. Pitchers seemed to adjust to Thames in such a way that completely exposed him. His May slash line of .221/.375/.416 still placed him a sliver above average… until he plummeted to a slash of .163/.267/.402 in June that placed him solidly amongst the least effective everyday players in baseball.
Thames has picked it up in July, hitting .300/.375/.540, but that 14-game sample size is not enough for me to dispel the growing trends from the last two months. So, Milwaukee, here’s a hot take for you: After thorough research including the above, I have concluded that Jesus Aguilar should be the Brewers’ starting first baseman.
I know, I know, it is sacrilege for me to call for the removal of Milwaukee’s newest favorite son. But the numbers don’t lie. Since the start of May, Aguilar has outperformed Thames by a significant margin. To show you this, I will present you with their statistics since May 1st.
First, let’s start on offense. To begin, we will look at each player’s Weighted Runs Created Plus (wRC+), a rate statistic that attempts to credit hitters with the true value of each offensive outcome. Park factors (e.g. the thin air of Coors Field) and the current run environment are considered, and the “average” player is scaled to be equal to “100”. Each subsequent point above or below 100 is a percentage point above or below average, so if a hitter has a wRC+ of 125, they have been 25% more productive of a hitter than the league average. This statistic will allow us to fairly evaluate Thames’ and Aguilar’s offensive contributions since the beginning of May.
We’ll begin by looking at their wRC+ facing lefties and righties, with no splits. Since May 1st, Aguilar has a wRC+ of 146 in 165 plate appearances. In the same time frame, Thames has a wRC+ of 96 in 257 PA. Aguilar has overall been the superior offensive threat.
The splits against right and left-handed pitchers tell a much fuller story. Before breaking down their performances into righty/lefty splits, one may think that Thames has done better against righties and Aguilar has proven more effective against lefties. That is not the case. Thames’ right/left wRC+ split is 121/20 (yes, you read the “20” right). Aguilar’s is 136/167. We can take a couple thoughts away from this.
First, while Thames has been 21% better than the league average against righties since May according to his wRC+, Aguilar has dwarfed that (36% better than league average), throwing away suggestions of a platoon where Aguilar faces lefties and Thames faces righties. Thames could certainly be justified as being in the line-up against a righty, but why do that when you have a player in Aguilar that could be 15% more effective? Ideally, the Brewers could fit both in the line-up against righties, but Thames’ and Aguilar’s lack of positional versatility prevents that from happening. Thames has at times played some left field, but his defensive performance has graded out extremely poorly there, which takes away from the positive effect of having his bat in the line-up against a righty.
Second, we gather that Thames has not been effective in any way, shape, or form against lefties. Aguilar should be getting every at bat as the Brewers’ first baseman when they face a lefty, no doubt. At the least, the Brewers should be platooning Thames and Aguilar based on handedness, if they decide to not make Aguilar a permanent fixture in the line-up.
Finally, their individual defensive contributions provide the icing on the cake for Aguilar’s case. Two common sabermetrics used to evaluate defense are Defensive Runs Saved (DRS) and Ultimate Zone Rating (UZR). Aguilar trumps Thames in both categories. While the differences are not drastic (Aguilar has a DRS of 1 while Thames measures in at -2), those slight disparities could mean a play here or there that decides a win or a loss. I would much rather have the player on the field that gives me the best chance of winning, which offensively and defensively looks to be Aguilar.
Eric Thames earned a long leash with his April performance, no doubt. But with the Brewers slipping significantly, it is time to tinker with what they have and right the ship. That means giving Jesus Aguilar a chance at starting in place of Eric Thames. The numbers don’t lie.
Your move, Craig Counsell.