As has been the case for each of the past several seasons, the Phillies’ rotation remains the team’s greatest strength. Their starters rank fifth in MLB in ERA and first in strikeouts, K-BB%, and SIERA. They trail only the Mets in FanGraphs WAR. Philadelphia’s continued success in this area has plenty to do with the talent the team has acquired and developed, but health has been another critical factor. In an age when arm injuries are a greater concern than ever, the Phillies have done an excellent job of keeping their pitchers on the field, and they have reaped the rewards. As Matt Gelb of The Athletic pointed out this morning, the Phillies were the only team in Major League Baseball not to make any major league pitching transactions during the first month of the season; the 13 pitchers on their active roster right now are the same 13 they started with on Opening Day.
Philadelphia’s pitching staff will grow healthier still on Sunday when left-hander Ranger Suárez is reinstated from the injured list. He has been out since the spring with back tightness. There is no doubt the Phillies will be pleased to have Suárez back on the bump. An All-Star for the time last summer, he has pitched to a 3.27 ERA and a 3.92 SIERA in 537 innings since the start of the 2021 season. He has been particularly dominant in October, with a 1.43 ERA in 10 postseason appearances (eight starts). No active pitcher has thrown more postseason innings (37 2/3) with a lower ERA. Nevertheless, Suárez’s return raises a difficult question for the Phillies that few other teams are lucky enough to have to answer: What are they going to do with all of their starting pitchers?
The Phillies are one of just five teams to have used only five starting pitchers so far this season. Zack Wheeler has continued to shine in his age-35 campaign, posting a 3.48 ERA and a 2.52 SIERA with 57 strikeouts across an MLB-leading 44 innings of work. Meanwhile, offseason trade acquisition Jesús Luzardo has looked unexpectedly ace-like himself, with a 1.73 ERA and a 3.12 SIERA through his first six starts with his new club. Cristopher Sánchez put an injury scare last week behind him, and his 3.54 ERA and 3.00 SIERA suggest he’s picking up right where he left off in his All-Star 2024 season. Aaron Nola has struggled at times, pitching to a 5.40 ERA, but his underlying numbers (3.63 SIERA, 3.58 xFIP) are stronger, and he has given the Phillies at least five innings in all six of his starts. Finally, Taijuan Walker has been a pleasant surprise as the no. 5. After an ugly 2024 (7.10 ERA, 5.25 SIERA), Walker has been much more effective so far this year. His 2.78 ERA might not be sustainable, but his 4.41 SIERA paints the picture of a capable back-end starter. That’s the kind of pitcher the Phillies hoped they were signing when they gave him a four-year, $72MM contract in December 2022.
It’s not up for debate who Suárez would replace if the Phillies decide to stick with a traditional five-man rotation. Walker might have a sub-three ERA right now, but he’s not the same caliber of pitcher as any of Wheeler, Luzardo, Sánchez, or Nola. If his dismal performance last season wasn’t enough to prove that, his 20% strikeout rate and 10% walk rate in 2025, both the worst rates among Phillies starters, should do it. The question, however, is whether the Phillies would consider keeping all six arms in circulation once Suárez returns.
Asked exactly that on Tuesday, manager Rob Thomson offered a cagey response. “Possibly,” he told reporters, including Noah Levick of NBC Sports Philadelphia. “We’re kind of walking through that a little bit right now.” In contrast, Gelb wrote this morning that the Phillies are “highly unlikely” to use a six-man rotation. That said, even Gelb didn’t shut down the idea entirely, and he acknowledged that sticking with a five-man rotation would “prompt a tough decision” for the Phillies to make.
The crux of the issue is that the Phillies need Walker – they just don’t need him right now. As long as Wheeler, Nola, Luzardo, Sánchez, and Suárez are healthy, Walker is all but irrelevant on this team. Yet, rotation depth is essential to get through a 162-game season, even for a team with a strong track record of keeping pitchers healthy. Walker proved how valuable he can be when he stepped in for Suárez during the first month of the season. The Phillies surely want to have him as an option again should any of their top five starters suffer an injury.
However, if the Phillies don’t keep Walker in the rotation, they’ll have to move him to the bullpen. They don’t have the option to send him down to Triple-A, where he could stay stretched out and ready for his next big league opportunity. It’s not that the Phillies don’t have room for Walker in their bullpen; he would almost surely be an upgrade over Carlos Hernández. The eighth man in Philadelphia’s arm barn has given up eight runs in 11 innings, striking out eight and walking seven. His 10.01 Statcast xERA is among the worst in the sport. The concern is that Walker wouldn’t be as effective yo-yoing between the bullpen and rotation as he is right now after having had a full spring training to prepare as a starter. A six-man rotation would allow the Phillies to keep Walker stretched out and pitching on a consistent schedule.
A six-man rotation would also give the rest of Philadelphia’s starters some additional rest, which could prove critical in helping them all stay at full strength down the stretch and (potentially) into October. This isn’t an option for most teams because it’s hard enough to find five MLB-caliber starters, let alone six. It would make sense for the Phillies to take advantage of this unusual opportunity for as long as they have a surplus of healthy arms.
Of course, a six-man rotation has its downsides, too. For one, it would lead to fewer starts for the Phillies’ best pitchers. In other words, it would diminish what has been the team’s greatest strength so far this season. What’s more, the Phillies have two off days coming up in the next two weeks (May 5 and 15). With a six-man rotation, there would be times when their starters were waiting a full week between outings. It’s fair to wonder if that’s too much time off. Rest is good. Rust is not. It is also important to think of the ramifications a six-man rotation would have on the bullpen. Philadelphia’s bullpen has struggled enough this season as it is, producing a 5.03 ERA and eight blown saves. Those numbers might be even worse if they’d had to split the 98 1/3 innings they’ve pitched so far between seven arms instead of eight. The team could ameliorate this problem somewhat by cycling through the optionable arms at the bottom of the 40-man roster or taking full advantage of the waiver wire, but that’s hardly the smartest bullpen strategy long-term.
Lastly, the Phillies need to consider the Andrew Painter of it all. The top prospect in the organization and one of the top pitching prospects in the sport, the 22-year-old righty is currently rehabbing from Tommy John surgery. His goal is to make his MLB debut at some point this summer. If everyone else is healthy when Painter gets the call, that could be the ideal time for the Phillies to switch to a six-man rotation. They could push their starters a little harder now with the understanding that some respite would be coming later in the season.
Phillies pitching coach Caleb Cotham recently told the Philadelphia Inquirer’s Scott Lauber, “We’re okay with not chasing a win today to win a bunch of games down the road.” While he wasn’t directly addressing the idea of a six-man rotation when he spoke those words, he nonetheless did a good job laying out the argument for such a strategy. One or two fewer starts from arms like Wheeler, Sánchez, Luzardo, Nola, and Suárez early in the season could mean more starts (and better starts) from all of them when it matters more. Moreover, keeping Walker in the rotation now could help prevent depth issues down the line. With that said, the argument against a six-man rotation is robust, and the most recent reporting suggests it’s still unlikely.
So, what do MLBTR readers think? Would the Phillies be smart to try out a six-man rotation, even just temporarily? Or would they be better off sticking with a traditional five-man set-up and moving Walker to the bullpen? Have your say in today’s poll:
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Photos courtesy of Nathan Ray Seebeck-Imagn Images.
