Stat Chat: Finding Future Closers, You Got It (The Right Stuff+)

The early bird gets the worm, and nowhere else are there more worms to be had than the waiver wire of available relief pitchers in your league. Each year we watch the demise of established capital-C “Closers”, who cost fantasy managers a decent penny in draft price, as other fantasy managers scoop up their understudy relievers from the waiver wire. To get an edge in this relief pitcher rat race, people play body language specialists, trying to read into every word a manager says in spring training attempting to “The Mentalist” their way into figuring out who will receive the coveted save opportunities. Watching this horrible rat race you may say, is there a better way to know which reliever to stash without reading the tea leaves on manager interviews? The good news is there is, just follow the pitch modeling numbers and trust that the “nastiest” pitcher with the highest Stuff+ will rise to the top of the bullpen hierarchy.

We have had publicly available Stuff+ numbers for several years now, and while their ability to predict starting pitcher efficacy is hit or miss, they’ve been incredibly predictive for reliever success. Simply put, higher Stuff+ leads to more swing and miss, more swing and miss means more strikeouts, and strikeout rate is one of the best predictors of reliever success (no one wants a sinker balling contact closer unless it’s Zack Britton). Often, projections will allocate Saves based on past stats, so during preseason projections may assume whoever had the most saves the previous year will get the bulk of opportunities the following season. However, as the season progresses there will be pressure for a reliever with more success to assume the closer role, which we now know is most likely whoever has the highest Stuff+. 

Anecdotally you see this play out in real time over the course of a season all the time. You have Giovanny Gallegos, who is the “established” closer who has assumed the 9th inning role based on his previous experience. Then there is the “super nasty” youngster Ryan Helsey, who has the ERA that starts with “0.” and everyone in St. Louis is talking about this hot young gun that throws a bazillion. Eventually, as Gallegos blows a few save opportunities (as closers naturally do), there is pressure for the young star reliever to take over the closer role. It’s the classic tale of old and busted vs new hotness:

Now let’s look at this story from a projection vs Stuff+ perspective. Coming into the 2022 season, the Steamer projected Save totals for the Cardinals relievers were:

• Giovanny Gallegos – 23
• Chris Stratton – 8
• Ryan Helsey – 0

their Stuff+ numbers, however were:

• Giovanny Gallegos – 103
• Chris Stratton – 93
• Ryan Helsey – 128

So before the season started, it was visible that there was a skill gap between the assumed closer and the eventual closer. This is even more important in 2025 because the alignment of Stuff+ and bullpen roles have become closer in recent years. Here’s a chart that shows a player’s average Stuff+ based on who on the team had the most saves that season (showing 2021-2024):

Back in 2021, the reliever who had the 3rd most Saves on the team had on average the same Stuff+ number as whoever had the most Saves on the team (the closer), but in 2024 teams are more and more identifying Stuff+ as being important, and the proof is in the fact that the relievers who get the most Saves (the closer) and 2nd most saves (co-closer / setup man) have much higher stuff+ number than in previous seasons.

Bringing this to practical terms in 2025, this is why you have fantasy managers closely watching Peter Fairbanks vs Mason Montgomery, Ryan Pressly vs Porter Hodge, Kahnle/Brieske/Holton vs Will Vest. There hasn’t been any tea leaves to read into what Kevin Cash had said, but it doesn’t take The Mentalist to know that the second Fairbanks suffers an injury, or has back-to-back shaky outings, the youngster with the Stuff+ advantage will be ready to take over.  Savvy managers should look to stash these arms now and reap the benefits later.  You have the information, act on it.