Both the Phillies and Blue Jays are hoping to bolster their starting rotations by reinstating an All-Star right-hander from the injured list later this month. Aaron Nola has not pitched for Philadelphia since mid-May, when he hit the IL with a sprained ankle. While he was originally expected back in June, he suffered a stress reaction in his rib cage that prolonged his IL stint. He is now finally nearing his return. Earlier this month, MLB.com’s Todd Zolecki reported that Nola could rejoin the Phillies after three rehab outings; he has since made his first two, striking out six over 6 2/3 total innings at Triple-A Lehigh Valley, giving up one earned run on seven hits. Per Lochlahn March of the Philadelphia Inquirer, Nola is expected to make his next (and possibly final) rehab start this Tuesday.

Meanwhile, Shane Bieber has been recovering from Tommy John surgery since last April. A free agent over the winter, he re-signed with the Guardians, but Cleveland flipped him to Toronto ahead of last month’s trade deadline. He had already begun a rehab assignment in the Guardians system, and he picked up right where he left off with his new team, tossing five innings of two-run ball for the Triple-A Buffalo Bisons last weekend and 5 2/3 yesterday afternoon. Blue Jays manager John Schneider told reporters (including Sportsnet’s Shi Davidi) that Bieber will most likely require one more rehab start before he’s ready to make his 2025 debut.

When Nola and Bieber return, their teams will have to figure out how to integrate them into rotations that have been functioning just fine in their absence. Since Nola last pitched on May 14, Phillies starters rank second in MLB in ERA but first in FIP, xFIP, SIERA, strikeout-to-walk ratio, innings per start, and FanGraphs WAR. Their current starting five includes Cy Young contenders Zack Wheeler and Cristopher Sánchez; Ranger Suárez, who might have been a Cy Young candidate himself if he hadn’t missed the first five weeks of the season; Jesús Luzardo, whose peripherals have stayed strong, even though his ERA has shot up after a hot start; and Taijuan Walker, who has bounced back from a dreadful 2024 campaign to post an ERA in the mid-3.00s as both a starter and a reliever.

Nola had a rough stretch of starts to begin the season, pitching to a 6.16 ERA in his first nine outings. Yet, it’s important to consider that a nine-run blow-up outing two days before he hit the IL significantly affected his surface-level stats. Moreover, several of his underlying numbers suggest he was much better to start the 2025 campaign than his ERA would have you think. His 3.77 SIERA this year is almost identical to his 3.72 SIERA from 2023-24, and while his FIP sits at 5.04, his xFIP is a much more respectable 3.65. He also boasts a lengthy track record of major league success. Long story short, there is no question he will have a spot in Philadelphia’s rotation upon his return.

The most straightforward course of action for the Phillies once Nola comes back would be to move Walker back to the bullpen. While he has pitched to a 3.48 ERA in 13 starts, his 4.64 SIERA out of the rotation is much less promising. It’s also impossible to forget just how much he struggled as a starter last season, producing a 7.18 ERA and 5.11 SIERA in 15 starts. However, the Phillies might also want to take advantage of the fact that Walker is throwing well right now. After all, most teams don’t have the luxury of six healthy, MLB-caliber starting pitchers.

Luzardo missed significant time with injuries in 2022 and ’24, and only once has he pitched a full, qualified season. Suárez has never qualified for the ERA title, topping out at 155 1/3 innings in 2022. Before this year, Nola could claim to be the most durable pitcher in the game, but his health is now something of a question mark. Wheeler’s health, too, is something to monitor after he underwent an MRI for shoulder soreness earlier this month (per The Athletic’s Matt Gelb). It came back clean, and the team doesn’t appear to be worried, but Wheeler is 35 and critical to his team’s World Series aspirations. Finally, Sánchez hasn’t given the Phillies any reason to worry so far, but the one-two punch of Wheeler and Sánchez has been paramount to Philadelphia’s success in 2025. Keeping both of them at full strength is a top priority.

So, it’s not hard to understand why a six-man rotation might appeal to manager Rob Thomson, especially with his club having just begun a stretch of 24 games in 25 days. Indeed, Charlotte Varnes of The Athletic reports that the skipper will at least consider switching to a six-man cycle when Nola comes off the IL.

It’s worth noting that the Phillies also thought about using a six-man rotation earlier this season, only to ultimately stick with the traditional five-man setup. When Suárez was nearing his return from the IL in May, Thomson fielded questions about adding Suárez to a group that already included Wheeler, Sánchez, Nola, Luzardo, and Walker. Could it happen? “Possibly,” he said at the time. “We’re kind of walking through that a little bit right now” (per Noah Levick of NBC Sports Philadelphia). Yet, Gelb suggested the Phillies were “highly unlikely” to go with a six-man rotation, and he proved to be correct. The circumstances are undoubtedly different in August than they were in May, but there’s a good chance the same outcome will prevail, and the Phillies will return to the five-man rotation they had always planned to use before injuries got in the way.

Toronto’s rotation has not been nearly as strong as Philadelphia’s this year, but the Blue Jays have been in much better shape since Eric Lauer forced his way into the starting rotation and Max Scherzer came back from the injured list, joining the steady and reliable trio of Kevin Gausman, José Berríos, and Chris Bassitt. Dating back to the week of Scherzer’s return, Blue Jays starters have a 4.00 ERA in 41 games. They rank 10th in both SIERA (3.93) and FanGraphs WAR (3.1). That’s a notable improvement from their performance over the three months prior, when they pitched to a 4.65 ERA (26th in MLB), a 4.16 SIERA (18th), and just 2.7 fWAR (27th) in almost twice as many games.

As is the case for the Phillies, there is really only one solution if the Blue Jays want to keep a five-man rotation when Bieber joins the squad: move Lauer to the bullpen. However, Lauer has been far more than just a stopgap for Toronto. In 18 games (12 starts), the southpaw has a 2.59 ERA and 3.62 SIERA. He has yet to allow more than three earned runs or seven hits in a start this year. His middling stuff and unimpressive track record are valid causes for concern, but there’s no denying how well he’s pitched. Since he formally joined the starting staff in mid-June, one would be hard-pressed to argue he hasn’t been better than all four of his much more established rotation-mates.

Much like with Nola, there is no question that Bieber, the 2020 AL Cy Young winner, will have a spot in Toronto’s rotation when he’s ready for it. Thus, Schneider told Davidi that a six-man rotation is “a definite possibility,” at least for “10 days or two weeks.” Needless to say, such an arrangement would be great for Lauer. Not only would he get to keep his job in the rotation a little longer, but some extra rest would probably do him well, considering he’s never pitched a full, qualified season. Extra rest would also benefit the injury-prone, 41-year-old Scherzer and the returning Bieber. On the other hand, it might not please the workhorses Gausman, Berríos, and Bassitt, each of whom has pitched just about every five games like clockwork since he arrived in Toronto. Unlike the Phillies, the Blue Jays have several off-days coming up, so a six-man rotation could mean that, at times, their starters would go a week between outings. Any potential benefits of a six-man rotation would be cancelled out if the extra time off negatively impacts any of their veteran arms. The Blue Jays would also have to consider the fact that their bullpen, a group that has struggled to a 8.48 ERA over the last two weeks, would be pitching one man down.

Images in article courtesy of Reggie Hildred, Imagn Images (Nola) and Ross Cameron, USA TODAY Sports (Bieber).