How Should Christian Yelich's Speed Affect Our Perceptions of His Power?

Since fracturing his kneecap on a foul ball in late 2019, Yelich has fallen short of the high standard of performance he set over the two seasons leading up to that injury. He might well have won back-to-back MVP awards, if not for that misfortune, but his last three years have been much more pedestrian. The stakes of that situation rose for the Milwaukee Brewers after Yelich signed a nine-year, $215-million deal, which is taking up significant space in their budget. 

With the Brewers’ success so dependent on the performance of Yelich, it might seem like he has become a below-average player. What some fans might not realize is just how good Christian Yelich was, and how difficult it will be for him to ever regain that form. 

It’s obvious that Yelich was an MVP in 2018, with a slash line of .326/.402/.598, and he was MVP-worthy in 2019, with a slash line of .329/.429/.671. While these statistics do give a little bit of insight as to the power Yelich held, they don’t completely capture the magnificence of those two years. 

Baseball is filled with statistics that go unnoticed, such as stolen bases, caught stealing, sacrifice flies, and double plays grounded into. This can also play a part in determining the performance of a player. One statistic that was developed to determine how a player contributes to the team is Speed-Adjusted Slugging Percentage (SaSLG). The idea of this statistic is that a single then a stolen base has the same impact as a double during a game, and the number of times you ground into a double play can show how often you have a negative impact.

The formula for determining SaSLG is:

(TB + SB + (-2)*(CS)  + (-1)*(GIDP)) / At Bats
 
This result is then able to be compared to the speed-adjusted slugging percentage of a player who has never stolen a base. The table below shows how SaSLG can be utilized to compare two players with separate talents.

When looking at the slash lines of Jon Berti and C.J. Cron, we often immediately come to the conclusion that Cron is the better player, holding an OPS of .805 while Berti has an OPS of .685. However, when you start to compare them through speed-adjusted slugging percentage, their quality in offensive performance isn’t as drastic as it might appear, with Berti having a SaSLG of .423 and Cron having a SaSLG of .458. 

With this information on SaSLG, we can compare the performance of Yelich over his career with the table below.

Yelich had a very good year in 2018 when looking at his SaSLG, but was phenomenal in 2019, performing 69.4% better than the league average (.418). However, since the start of 2020, he is performing slightly below the league average. 

This statistic can also be misleading in determining a player's overall performance. This doesn’t take into account walks or times hit by pitch, where a walk and a stolen base would equal the same number of bases as a double. To counter this, we can play with this statistic by including the total amount of bases acquired and lost divided by the total amount of chances given to a batter. This statistic would be changed to, (Total bases + Stolen Bases + Base on Balls + Hit by Pitch + (-2)*Caught Stealing + (-1)* Double Plays Ground Into) / Plate Appearances).

Using this statistic, we can see that Yelich’s Adjusted SaSLG in 2021-2022 has been producing similar numbers prior to his MVP season in 2018-2019. So why does it feel like he has still fallen short these past two seasons? The difference is that he's been relying on getting walked more often, which in turn has lowered his RBI totals, making him look closer to his 2014-2015 self. To put that into perspective, Yelich had 179 RBIs between the 2016 and 2017 seasons, while he only had 108 RBIs between the 2021 and 2022 seasons. 

By looking at the data, Yelich isn’t a bad player, but he wasn’t worth $26 million in 2022. The good news is, his career isn’t over, and he still has the potential to return to MVP form sometime during the remaining six years of his contract. Yelich might not be the all-star he was in 2018-2019, but he hasn’t fallen too far from where he used to be.