Aaron Bummer Comes to Terms With the White Sox

This morning, the Chicago White Sox came to terms on a contract extension with reliever Aaron Bummer. The news was originally reported by Bob Nightengale of USA Today on Twitter.

The shrewd Chicago #Whitesox keep locking up their young talent: They are signing reliever Aaron Bummer to a 5-year, $16 million contract. It’s the largest extension given to a non-closer who has yet to qualify for salary arbitration in #MLB history.

— Bob Nightengale (@BNightengale) February 22, 2020

For the Chicago White Sox, this is a very good signing and one that is low-risk. While relief pitchers are volatile from year-to-year and projections can’t be accurately drawn up on paper, Aaron Bummer is a core piece of the White Sox bullpen. Given some of the uncertainty regarding the White Sox starting rotation, Chicago will need solid bullpen options such as Bummer.

Aaron Bummer in 2019

Last year, Aaron Bummer posted a 2.13 ERA over 67.2 innings of work during his third season in the big leagues. Over that span, Bummer posted a 3.41 Fielding Independent Percentage (FIP) along with a 8.0 K/9 rate.

While the surface-level numbers are mediocre overall, the underlying metrics are where things get interesting. During the 2019 regular season, Bummer developed the reputation of being a sinkerball specialist for the Chicago White Sox. According to Baseball Savant, Bummer threw his sinkerball 67.7% of the time last year and worked that pitch up and down throughout the strike zone.

With his sinkerball, Bummer held opponents to a .195 batting average and a .268 slugging percentage. In addition, the sinkerball accumulated to a 16.3% Whiff Rate for Bummer and had a spin of approximately 2,033 RPM. Overall, it was a very effective pitch for Aaron Bummer and is a big reason why the White Sox feel as though Bummer will be a valuable part of the team this coming season.

Aaron Bummer’s Cutter

While the sinkerball was Aaron Bummer’s most effective pitch last season, his cutter was his next most effective pitch. Bummer relied on his cutter approximately 20% of the time last season. With the cutter Bummer mainly focused on down and away especially in the lower right quadrant of the strike zone.

Bummer threw approximately 208 cutters last year and held opponents to a batting average of .087 with it. Where Bummer really shined with his cutter was in preventing the opponent from doing damage with that pitch especially when it came to slugging percentage. Opponents posted a .109 slugging percentage on Bummer’s cutter last year.

Beyond all of that, Aaron Bummer was able to put a lot of sink and drop on his cutter. That was one reason why it was so effective for him and why many of those pitches ended up where they did in correlation to the strike zone. According to Baseball Savant, Bummer’s cutter averaged 35.9 inches of drop last season. The only pitch with a higher drop rate – Bummer’s sinkerball at 36.0 inches.

Left-Handed Value

Finally, outside of the numbers and the metrics, a big reason why the Chicago White Sox came to an agreement with Bummer on this extension was because of how they view him overall. With all of his pitches, Bummer induces a lot of ground balls which is extremely important in baseball today. With the number of home runs that were hit last year, teams are constantly looking for ways to keep the ball on the ground and in the ballpark.

In regards to Aaron Bummer, the Chicago White Sox know they are getting a valuable left-hander who can induce those ground balls. Furthermore, the White Sox know they are getting someone who can pitch during critical moments of a ball game.

Last year, during high leverage situations that accounted for 107 plate appearances, Bummer held opponents to a batting line of .143/.208/.143. The Chicago White Sox view that as a huge upgrade for their team heading into the 2020 season. If the White Sox want to make it to the postseason, then they know Bummer has to be a pivotal component of their bullpen group.

Final Thoughts

In the end, no one can accurately predict how a reliever is going to perform year-to-year. However, the Chicago White Sox are making a smart bet by extending reliever, Aaron Bummer. Furthermore, it’s an extension that is affordable (five-years, $16 million dollars). With the role that relievers play in the game today, teams are always looking for affordable ways to find impact, late-inning arms. Aaron Bummer is just that and will be a critical part of the White Sox team this season.