A Simple Change in Pitch Mix Helped Duensing Flourish with Cubs

Brian Duensing apparently enjoyed his time with the Cubs so much that he took less money to stay in Chicago, agreeing Wednesday to a two-year, $7 million contract. Can you blame him? After the Cubs signed him for $2 million last season, the lefty reliever’s consistent performance gradually made him a staple in the ‘pen.

Prior to finishing 2017 with a 2.74 ERA, 3.57 SIERA, and 3.41 FIP, Duensing had ridden a roller-coast career arc. He debuted with the Twins in 2009 and played the Mike Montgomery role, shuffling between starter and reliever to the tune of a ~3.20 ERA over two seasons. But when given a full-time starter role in 2011, his ERA ballooned to over 5.00 and he was sent back to the bullpen. He had modest success there from 2013-2015 (3.86 ERA, 4.16 FIP).

At an age when most pitchers start to look like shells of their former selves, the 34-year-old Duensing’s posted his lowest ERA since a 2.62 in 2010. So how exactly did he find his way to the fountain of youth?

Duensing’s most noticeable change as a Cub was throwing fewer sinkers, as you can see in the chart below.

What really made a difference, though, was that he replaced his sinkers with curves. Comparing Duensing’s 2017 pitch usage to his pre-Cub days, we can see about a 2.5-fold increase in curves thrown.

Throwing fewer sinkers and more curves was a nifty strategy by the Cubs and Duensing. After all, only 13 percent of curves thrown by MLB lefties since 2007 had more dropping action. Perhaps this was one reason the front office felt comfortable signing Duensing in the first place, figuring all along that his career could be rejuvenated with a simple tweak in pitch usage.

Only paying Duensing $3.5 million over each of the next two seasons seems like a low-risk bet. While you never know how a soon-to-be 35-year-old pitcher will age, Duensing’s season with the Cubs last year was no fluke. New pitching coach Jim Hickey is no stranger to maximizing breaking pitches, so maybe we’ll see even more curves from the lefty next season.

Anything close to a repeat of Duensing’s 2017 performance would make this deal a huge bargain.

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