Breakout Mariners RHP Erik Swanson unsung part of dominant bullpen

There are a lot of things you can highlight from the Mariners’ 25-game hot streak where they’ve turned around from 10 games under .500 to within a half-game of the first American League wild card spot. Perhaps none is more eye-opening than what Seattle’s bullpen has done over the 22-3 stretch.

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Since June 21, the Mariners’ bullpen leads all of MLB in ERA (1.49), fWAR (1.8) and left on-base percentage (93.8%), and it ranks near the top in just about every other meaningful category. The Seattle relievers are also maintaining a 10-0 record with 12 saves over that period.

There are certain pitchers from the bullpen that stand out the most, like Diego Castillo and Paul Sewald, who usually get the highest-leverage spots, and Andrés Muñoz, a fireballer who has been on a tear with 14 straight scoreless appearances since mid-June. There’s somebody else who is deserving of a lot of credit, however, as Mariners analyst and former MLB pitcher Ryan Rowland-Smith pointed out on his weekly conversation on Seattle Sports’ Wyman and Bob.

“We’ve talked a lot about (Andrés) Muñoz, and Paul Sewald I can talk about all day… but Erik Swanson,” said Rowland-Smith. “I’m telling you, that kid is going to have some sustainability and be in this bullpen at the back end of it for a long time.”

Swanson, 28, was one of the less-heralded pieces of Seattle’s trade that sent James Paxton to the Yankees prior to the 2019 season, and his tenure with the Mariners started bumpy. He transitioned from a starter to a reliever in 2019, and he showed promise with a 3.31 ERA in 2021. The 2014 eighth-round pick has been lights out this year even after a short injured list stint and some time on paternity leave, as he owns a minuscule 1.04 ERA and 0.846 WHIP with 35 strikeouts to five walks over 26 appearances (26 innings).

Rowland-Smith points to Swanson’s command of a stellar split-finger fastball as a key to his success.

“There was the Erik Swanson who got drafted high and came up as a starting pitcher, and then there’s the Erik Swanson who started throwing the split – they’re two different dudes in my book,” he said. “… He’s just a different dude, he’s a different guy. And I know he’s had that (splitter) now for one-plus year, but it’s just exciting to see when a kid can come up, struggle a little bit at the beginning as a starting pitcher, trying to figure it out, and then all of a sudden starts really working hard on on a pitch. Now he’s just a mainstay in that bullpen and adding to that what is the best bullpen in the league, and he’s a big part of that.”

There was one use of the splitter that Rowland-Smith especially liked last week in the second game of the Mariners’ doubleheader sweep of the Washington Nationals when they needed to employ a bullpen game to allow their starting rotation some rest.

“He comes off the paternity list where he’s been out for a few days and he’s the opener when you really needed him to throw two innings in that situation, just dotting up strikes and just throwing splits and just making Juan Soto look silly on a ball he rolled over.”

You can listen to the full conversation in the podcast at this link or in the player below.

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