What Will the Mariners Get in Ryne Stanek? 

The Mariners added Ryne Stanek to their bullpen on a one year, 4-million-dollar contract with two million incentives. The Mariners added Stanek after recent arm issues from two of their main bullpen arms in Matt Brash and Jackson Kowar. The Mariners are reportedly concerned about Kowar and his arm issues, so adding Stanek was a welcome addition to the bullpen. 

The 32-year-old righty has been part of a major league bullpen for 6 years straight. Stanek has a 3.45 career ERA over 347 innings pitched. The Mariners drafted Stanek in the third round of the 2010 draft but didn’t sign. The Rays eventually drafted him as a first rounder in 2013. Stanek got famous as he was often used as an opener in Tampa Bay, even getting his giveaway item: A bottle opener.  

Since leaving the Rays, Stanek has been more of a late inning arm for the Marlins and Astros. He found great success with the Astros from 2021 to 2023, with a 2.90 ERA with the Astros. So, being in the same division, he is well known by the Mariners for that reason too. 

So, what are the Mariners going to get with Stanek? Most of all, a high velo fastball that averaged 98.2 mph on the gun. It’s Stanek’s main pitch, throwing it 64% of the time last season. He also mixes in his splitfinger and slider at about the same percentage (around 18%). While his fastball gets positive run value, his slider and splitter, were below average. It was also the case in his great 2022. The slider was below average, while the fastball was his best pitch. Splitter was slightly above average in 2022. That season Stanek pitched to a 1.15 ERA for the Astros, but a 3.19 Expected ERA. 

Let’s focus on his most recent season. While Stanek is still a productive arm, his season was closer to his expected ERA from the 2022 season. In 2023, Stanek pitched to a 4.09 ERA with a 4.04 Expected ERA. If you compare his 2022 to his 2023, you see some mixed results: 

As you can see, he improved his walk rate, but overall, most numbers declined for Stanek. His HR per nine went up from 0.3 to 1.4. While I believe it wasn’t expected that Stanek would repeat that HR rate, it’s still a sign for what to come.  

So, let’s take a look at what Stanek did differently on his pitches. Stanek increased his fastball usage for good reason, as it was by far his best pitch. As the production on the fastball went down, it was still pretty good. His Splitter was actually solid if you look at his slash line against the pitch, as it was a good pitch to get a whiff on. It got below average run value, as it’s a very goodpitch for many pitchers who use them. A .189/.265/.297 slash line against the Splitter, makes this a useful pitch. The Splitter also got a 46.6% Whiff rate, making it a true strikeout pitch.  

The issue was the slider and it’s an interesting pitch for Stanek. While his hard-hit rate vs the slider was the lowest of any of his pitches, he still allowed his fair share of damage. Hitters had a .519 slugging against the Slider. However, his expected numbers against that pitch weren’t that bad. Still, since having a tremendous Slider in 2021 (.105/.166/.184), his production with that pitch has dropped. Last year, Stanek inches op drop diminished from 38.0 to 35.3, so he is getting less bite on the pitch. If that’s an easy fix for him? Watch out! 

Even if Stanek isn’t able to adjust with his slider, I believe the Mariners have found a good arm. Stanek is used to pitching in high leverage situations for a contending team. And at 32 it’s not like his fastball has diminished. That’s still a pretty elite pitch for the hard throwing righty. Stanek is also used in all types of roles and for the price the Mariners paid, it’s a tremendous deal. Stanek will be part of an already solid bullpen on paper, so to me he is a tremendous extra to get. Him in a bullpen with Munoz, Santos and hopefully Brash, this will be nasty to watch! Watch out AL West!