I was contemplating this week writing about the Phillies overall bullpen and pitching situation, and one of those topics was going to be about how I thought the Phillies should start moving starters to the bullpen, particular IronPigs RHP Seth Johnson. On Tuesday evening, Johnson came out of the bullpen for only two innings. Notably he only threw 25 pitches and came in for a clean inning and also did not pitch through the end of the game. It also looks to not be a one game fluke either.
What Does Seth Johnson Look Like as a RP?
Before talking about why they would make this move from a roster standpoint, it is helpful to know why Johnson makes sense as a reliever just from a pitching ride. As a starting pitcher, Johnson features a four seam fastball, slider, curveball, and splitter/changeup. The Phillies made some changes for Johnson already, he has moved from a more traditional changeup to a splitter. Neither has been a particularly good pitch, but his splitter has much more vertical separation from his fastball which allows him to tunnel it better. His curveball has also failed to miss bats and he has moved it aside more and more.
In 2025, he has thrown his fastball or slider 85% of the time and that is likely to stay true or increase as a reliever.
On the season, Johnson’s fastball has average 95.1 mph, up from 94.7 mph in 2024 in AAA. In his first two starts, Johnson saw his fastball touch 98 mph, but his average and peak velocity decreased as the season went on. Out of the bullpen on Tuesday he averaged 96.0 mph, peaked at 98.4 mph and was consistently up near the top of his range. Johnson’s fastball is not an elite pitch, but the Phillies have made some meaningful updates, getting him a little lower and flatter, which has also contributed to some more extension. The result has been a flatter approach angle with a little less ride, which has been an overall better shape, especially with Johnson pitching up in the zone more. This pairs well with his slider, which has been his best pitch. It is a gyro slider with a high spin that has sharper vertical break this season, meaning that Johnson can tunnel it better off of his fastball up in the zone. He has missed fewer bats with it so far this season, but he has thrown it in the strike zone much more while still limiting damage. Part of all of this working is that Johnson will need to throw more strikes. He does not need to fill the zone, but his fastball is a chase pitch and that requires the hitter respect that it could be a strike and for him to get strikes early in the count so he can expand the zone.
As a reliever, it is likely that Johnson will pitch up and out of the zone with his fastball while then using his slider more in the zone to steal strikes and keep hitters off of his fastball. The hope is that both pitches have a bit more velocity in short bursts which will help the fastball play up beyond its shape. I do expect him to mix in the splitter and curveball when there needs to be another look, but I would not be surprised if they are combined less than 10%. Unless he unlocks a completely unseen gear, Johnson is probably a multi inning middle reliever and not a late inning high leverage arm.
Why Make the Change?
The most obvious is that the Phillies need relief help, and at 3 months out from the trade deadline, it was unlikely that a major addition was coming. That means the Phillies will need to find some answers on some shorter basis. Johnson is unlikely to be available soon out of the bullpen, but this time period can help the Phillies make an assessment on his future and their needs.
The why for making this move for Seth Johnson in particular is also fairly straightforward. While injuries and late a conversion to pitching means that Johnson does not have a lot of innings under his belt, he is 26 years old. He also was added to the 40 man roster while rehabbing from Tommy John surgery in fall 2022. That means that barring a 4th option being awarded (which is possible given the injury and missed 2020 season) this is Johnson’s last option year. He is not ready as a starting pitcher and there is not a lot of runway to make the needed improvements.
This then feeds into the Phillies starting pitching depth. There has been a step back for Moises Chace in the early going, and there is a chance that Sanchez is more injured than it looks like. However, Ranger Suarez is now almost back, Taijuan Walker looks like actual depth, and Jesus Luzardo looks like a Cy Young candidate. In the minors, Andrew Painter is pitching now and Mick Abel has emerged as interesting starting pitching depth giving another layer of depth on top of the other swing man types like Alan Rangel and Kyle Tyler and the AA depth of Eiberson Castellano, Moises Chace, and Jean Cabrera. Overall, there is less room for Johnson to break in as a starter and much more need in the bullpen.