Perception and Reality Collide: Reviewing Aaron Bummer's White Sox Tenure

Bummer's time on the South Side ends with the happy chorus of many, but as it concludes it forces us to one more time look at the schism that exists within the Sox fan base and baseball fans, in general. We are still in an age where a sizeable enough segment of the sport's fans willfully choose to ignore new information that's available when it comes to measuring player performance. I'm continually baffled by the fact that baseball seems to be one of the only industries today where some refuse to accept new ideas that didn't exist before Grover Cleveland served his two nonconsecutive terms in the White House.

This isn't to say that fans of modern data are perfect either. Many stick on the polar opposite end of the spectrum, only choosing to look at data and discarding the elements of players' emotions and "feel" on the game because they can't be quantified. I've said it numerous times, and I will continue to say it, but living on either end of the spectrum is foolish to me.

As a former scrub JUCO pitcher, I have playing experience so I've been on the field in the heat of the moment. I also recognize that this game continues to evolve and we will continually develop new ways to optimize and evaluate performance. This is one of my favorite aspects of this great game. It's not stagnant, it's constantly evolving. I will forever be intrigued by how the game has continued to change. It doesn't mean that the game is necessarily better, it just means it's different.

Hell, there are plenty of aspects of today's game that I frankly don't like and don't find aesthetically pleasing. As a former hurler, I love dominant starters who take the ball and shove. But the fact is, there simply aren't a large number of starters today who can navigate a lineup three or four times. We've learned this through the use of data. Again, I don't particularly like the concept of bullpenning, but I understand it and why it's done in an effort to win a baseball game.

Two Sides of the Coin

Circling back to Aaron Bummer. He was the poster child for the analytics community that loves things like spin rate, expected, and fielder-independent stats. In his seven seasons with the White Sox, he posted a 3.84 ERA and 3.38 FIP with a 3.31 xFIP.

Bummer also posted a career .315 xwOBA, which is well above average.  This is a measure that takes into account metrics such as exit velocity and launch angle, essentially assessing the quality of contact surrendered. He had four separate seasons in which that number was below .300, including 2023, which is pretty elite. This is a big reason why many of his supporters, and I say this as someone who was for a time the conductor of the Bummer hype train, were so staunch in their defense of him.

What gets lost in this, however, are a few important factors. Bummer didn't throw enough strikes. In fact, his walk rate was in the bottom 4% of pitchers during the 2023 season. At 13.5%, that is simply too high for a late-inning reliever who is counted on in high-leverage spots. These walks often compounded problems that came either before or after the surrendering of soft contact that resulted in hits.

In many instances, that soft contact finding holes was a byproduct of shoddy White Sox defense, which simply can't be ignored. The other factor that can't be ignored is that Bummer would frequently put himself in these precarious positions as a result of falling behind in counts too often and seemingly trying to nibble within the strike zone.

The greatest frustration I had with Bummer, and one that I know was shared by many of his detractors, was the "deer in the headlights" look that he displayed frequently on the mound. I would've killed to have the natural stuff Bummer has. If I did, I would go right at any hitter that stepped in the box. I said almost nightly on the Sox On Tap postgame show that when he has the ball in his hand he should have the mindset that he will get any hitter on the planet out. But that didn't happen.

Not every pitcher is going to be outwardly expressive, which is fine, but Bummer was the poster child for what looked like pitching scared, and that's something that can't be quantified. While not everything that appeared on his final stat line was his fault, his inability to help himself shouldn't be ignored either.

You can cite his expected stats as a reason for optimism if you would like, and I can understand why you would. But I can also understand the old-school mindset that he doesn't have "it" between the ears. We hear fans of the latter category say all the time: "If you watch the game, you'll see he's not that good." I can tell you, as someone who watches the games every night that this is a simplistic way to look at things, just as it is to only pull up FanGraphs and look at his underlying metrics.

What to Make of Aaron Bummer's White Sox Tenure

Aaron Bummer is a confusing pitcher. He has great stuff and peripherals that any team would want in their bullpen. The performance hasn't consistently been in line with those peripherals, however, and that can't be ignored. Once again, I'll say that Bummer himself deserves blame for a lot of this.

Pitching behind in counts consistently at the MLB level will get you get destroyed on the mound today. Going out there and nibbling instead of attacking hitters is a losing strategy. If the Braves are to get the best out of Bummer, they need to find a way to get him pounding the strike zone with more conviction and consistency.

One thing I'll take away from Bummer's time on the South Side is that you can have great peripherals and expected stats showing that you're making quality pitches while also putting yourself in a position to be unsuccessful. The two aren't mutually exclusive. I wish baseball fans would understand it doesn't have to be all of one and none of the other. Like so many things in life, the truth lies somewhere in the middle. Bummer could certainly perform a lot better than he has now that he won't be pitching for the White Sox, but he is not absolved of blame for those negative results.