The White Sox Bullpen Could Be Special

The White Sox don’t need an elite bullpen to compete. They had the most valuable position player group in baseball in 2020, and that was without two stars, Yoán Moncada and Luis Robert, playing to their full potential. They also have a rotation that boasts two aces and a fair amount of rotation depth. Give them last year’s Phillies bullpen, and they’d still likely be able to fight for a playoff spot, especially in their division. Fit them with an average ‘pen, and their postseason expectations begin to look like more of a certainty.

Much to the chagrin of the other AL Central teams, Chicago’s bullpen doesn’t look like it’s going to be average, and it definitely doesn’t look like it will be awful. That much was made clear when the White Sox signed Liam Hendriks — the best reliever in this year’s free-agent class and at worst a top-three-or-four reliever in baseball — on Monday. Since the start of 2019, he has been nearly two wins more valuable than any other relief arm in baseball, posting a 1.79 ERA and 1.70 FIP in 110.1 innings. Our Depth Charts have Hendriks forecast for 1.6 WAR in 2021, tying him with Aroldis Chapman and Edwin Diaz for the highest relief WAR projection in baseball. With that considerable boost, the White Sox’ bullpen now projects to be the second-best in the majors, albeit with loads of free-agent talent still unsigned.

Hendriks answers the question of who will finish games for Chicago after the team’s closer of the past two seasons, Alex Colomé, became a free agent. But even though there’s a clear relief ace in the ‘pen, that doesn’t mean you should forget about the supporting players around him. The team’s bullpen had a good year in 2020, finishing with the seventh-best ERA in the majors. Colomé is the only key pitcher of that group who isn’t still on the roster (and Chicago reportedly still has interest in bringing him back). Here’s how the team’s key bullpen arms performed last year, looking only at pitchers who threw at least 10 innings in order to strip away the extremely small samples and stray position players.

Right away, you can see how adding Hendriks to this group makes it quite formidable. González and Cishek are free agents now, while Detwiler has moved on to Miami. What’s left behind is a very interesting group of arms, arguably headlined by Marshall. The White Sox are the fourth big league team of his seven-year career, and they are the team he’s enjoyed far and away the most success with. Over two seasons in Chicago, he’s worked a 2.45 ERA and 3.60 FIP in 73.1 innings, after pitching just 43.1 major league innings over his previous four seasons with a 7.89 ERA and 5.27 FIP.

It’s likely no coincidence that Marshall’s success in Chicago has coincided with a total reinvention of the way he pitches. The right-hander was rather reliant on his fastball, particularly his sinker, when he first got into the big leagues. But his velocity has slowly but surely dipped each year of his career, to the point where it is now two ticks slower than it was five years ago, and it always got hit hard. Clearly not fit to be a power arm, Marshall instead became a junk-baller.

The spike in changeup usage in 2019 had an immediate effect on the contact Marshall was allowing. After allowing an average exit velocity of 89.8 mph the year before, he was suddenly limiting opponents to an average of 86.9 mph. It also made him a platoon nightmare: Lefties hit just .221/.321/.279 against him in 2019, then .119/.213/.143 in 2020, a year in which he actually faced more of them than he did right-handed hitters. Marshall still wasn’t missing many bats, though, and that’s what the spike in breaking ball usage fixed in 2020. In nearly doubling his slider rate from the previous season, he bumped his K% from 19.6% to 32.3%, while also cutting his walk rate from 11.5% to 7.5%.

Joining Marshall on the above list are a pair of mid-20s arms who had incredibly impressive rookie seasons in 2020. Heuer, a 24-year-old righty, is mainly a sinker/slider arm whose two-seamer sits firmly in the high-90s. He seized a big league job early and finished the season in the 80th percentile in expected wOBA according to Statcast, and in the 86th percentile in whiff rate. Heuer’s success was hardly out of nowhere, given that he ranked ninth on Eric Longenhagen’s preseason White Sox prospect list. The same, however, can’t be said for 25-year-old right-hander Matt Foster. He wasn’t given nearly the same value as a prospect that Heuer was, but their rookie numbers wound up being extremely similar in many ways, thanks in no small part to a surprising and substantial velocity bump that Longenhagen discussed a bit in August.

As much as these three and others are expected to contribute in 2021, the best returning reliever on the White Sox didn’t even throw enough last year to show up in the table above. Left-hander Aaron Bummer, 27, suffered a biceps strain that ended his 2020 season after just 9.1 innings. That was a big loss to a club so enamored with his first three big league seasons that it took the unprecedented step of offering a contract extension to a pitcher who was neither a closer nor in his arbitration years.

Bummer earned that extension with a sinker whose dominance has approached that of Zack Britton’s. Already a good pitch in his first two seasons, its velocity took a major step forward that coincided with a significant increase in groundball rate, helping him cut his ERA in half from 2018 to ’19. If he’s healthy in 2021, it’s easy to see him settling into a set-up role ahead of Hendriks, making the final two innings of games hell on Chicago’s opponents.

And that still isn’t the end of the team’s high-leverage relief talent. On Longenhagen’s 2021 White Sox list, two of the top six prospects are relievers who got cups of coffee in the majors last year. The best of them is Garrett Crochet, a 21-year-old lefty who was drafted with the No. 11 pick last year and quickly pitched his way onto the MLB staff, where he overpowered hitters with a fastball that averaged over 100 mph. According to Longenhagen, the White Sox still plan to develop Crochet as a starter in the future. But because he’ll be on an innings limit in 2021, it makes a lot of sense to plug his electric arm into the big league bullpen and let him go to work there.

Zack Burdi, meanwhile, is more of a straightforward relief prospect at 25 years old. His development has been hampered by injury issues, but his fastball is still capable of hitting triple digits, and his secondary pitches are quite good too. He got hammered in his first big league trial in 2020, which lasted all of 7.1 innings, and his command could continue to give him fits. But his stuff is good enough that he’s always going to seem just around the corner from being a shutdown reliever.

Not all of these arms are going to make a big impact at the major league level. Injuries, sophomore slumps, and other potential obstacles could step in and take the legs out from under this group. But the possibilities presented by a bullpen like this are hard not to get excited about. Hendriks is a relief ace with years of health and postseason experience under his belt, and behind him are two very good veteran arms, quality depth like Fry and Cordero, and a long list of immensely talented young pitchers. Plus, there is the aforementioned collection of relief talent that remains on the free-agent market, and Chicago is one of the few teams that seems interested in spending money right now. In the 117-year history of the White Sox, they have never made the playoffs in back-to-back seasons. With a bullpen like this one, accomplishing that in 2021 should be only the beginning of their plans.