How the Cubs Fixed Julian Merryweather

The move to claim Julian Merryweather nearly 365 days ago would have gone under the radar for even the most ardent Cubs fans. There was little to be excited about a reliever who had shown such little success to date, and the Cubs have a habit of claiming and then designating for assignment these types of players throughout the Hoyer era, so there was a good chance he'd never make an appearance for the Cubs. Instead, Merryweather would finish the season with an ERA in the mid-3s, an xFIP of 3.61, and accumulate nearly a win of value per FanGraphs, becoming a useful leverage reliever and one of the staples in the Cubs pen. 

Digging into the data on Merryweather, the surface numbers look much improved, the most glaring of which was his K%. Sitting at a mediocre 24.3% in 2022, the Cubs squeezed a 10% jump in strikeout percentage out of the righty, as Merryweather saw his K% rise to over 32%. The reason behind the jump in strikeout rate is likely behind the 10% whiff% increase Merryweather saw from 2022 to 2023, specifically against left-handed hitters. A pitcher who always boasted an average fastball velocity of over 97mph, Merryweather was finally turning his stuff into results. But the strikeouts didn't come from thin air, and a deeper dive into Merryweather can help pinpoint where the changes occurred. 

Before coming to the Cubs, Julian sported a four-pitch mix: a four-seam fastball, a slider, a sweeper, and a changeup. Leaning heavily on the fastball, Merryweather threw this pitch to righties over 50% of the time. In 2023, the Cubs made a pitch mix change as Merryweather now threw the four-seam just 30% of the time against righties, leaning heavily on the slider (60%+). Against left-handers, he increased the usage of his slider, which sounds counterintuitive in theory as sliders traditionally work best against same-handed hitters. While Merryweather remained somewhat susceptible to left-handed hitters (left-handers have a wOBA of .305 against him compared to a .280 against righties), his slider shows far more vertical break than horizontal, making it useful against either side.  Cutting out his sweeper against left-handers entirely also helped. 

More importantly, the consistency and shape of his pitches improved. Below are charts that show the horizontal and vertical movement of his pitches from 2023 (left) and 2022 (right). Notice how more consistent the changeup (depicted in purple) is. Even though he decreased the pitch usage, the pitch is far more concentrated in the same area. He also added a sweeper (salmon/pink) instead of a curveball, which began to distinguish itself and separate itself from the slider (green). Again, it's a pitch he doesn't use often, but it gave him a new addition to his arsenal... something with true horizontal instead of vertical movement. 

The overall result can be seen in the amount of swings and misses that Julian Merryweather got between 2022 and 2023. Looking again at the charts provided by TruMedia, Merryweather did much better in 2023 (left) compared to 2022 (right). He continued to get chases below the zone as he had done previously but also began to get more swings and misses in the zone. It should be noted that Merryweather did walk more hitters in this approach, but gaining more swings and misses in the zone will be good for a pitcher who will walk a few more. 

Overall, it becomes clear that Julian Merryweather's time in Chicago last year resulted in an improved pitcher. Gains in consistency, shape, and pitch mix transformed a pitcher who always had good stuff into a pitcher who finally began showing impressive results. I don't think Julian Merryweather is a guy you want closing, but he's also a great asset in the 7th and 8th innings and a pitcher capable of getting those essential swings and misses when needed. The Cubs shouldn't refuse to add bullpen help (with players like Robert Stephenson, Phil Maton, David Robertson, etc, still available). Still, they can also feel comfortable moving forward with Merryweather as a staple in the bullpen for 2024.

Where do you think Julian Merryweather fits into the Cubs' 2024 bullpen plans? Are there other pitchers you think can make the kinds of jumps he did? Let us know in the comment section!