Can Shelby Miller be a Different Kind of September Call-Up?

This week at North Side Baseball, we've covered a few players who we think could be on the precipice of being a September call-up as rosters set to expand next week. Teams will be permitted to bring up two more players on their 40-man roster for the final month of the season. We looked specifically at pitcher Jaxon Wiggins and catcher Owen Ayers. Both of these players are the "typical" kind of player we see teams add with expanded rosters: prospects with a specific skillset that could help a team down the stretch, but who have yet to establish themselves. Shelby Miller, who has accrued over 920 innings in the majors to date, certainly breaks this mold, but he could be due for the same type of treatment as his much younger counterparts. 

Miller, a 35-year-old converted starting pitcher, has had his share of ups and downs over a long career. He was a first-round pick by the St. Louis Cardinals in 2009, and after being part of some very good Cardinals teams, he was traded to Atlanta for a strapping outfielder named Jason Heyward. He posted a promising 3.7-fWAR season in 2015 as a 24-year-old with the Braves. This excellent start to his career caused the Arizona Diamondbacks to become enamored with him, going as far as to trade their recently drafted top prospect, Dansby Swanson, to Atlanta to acquire him as a lead in their new-look rotation. After his strong start, however, the right-handed pitcher really struggled to find his place in the league, having a terrible 2016 in the desert and then eventually bouncing from organization to organization. He even made three appearances for the Cubs in 2021. (If you don't remember it, don't worry. It was just for two innings total and they were highly forgettable.)

Things started to look up for the journeyman at last in 2023. While Miller had what seemed like a successful 42 innings with the Dodgers (posting an ERA of 1.70), however, the underlying data suggests that this may have been smoke-and-mirrors. Another down year in 2024 while pitching out of the Tigers' bullpen put his career on ice. Miller, once again, looked like he would struggle to find his place. Then, just last year, a return engagement with the Diamondbacks revived Miller's career—and the under-the-hood numbers looked a lot better this time. He was traded to Milwaukee at the deadline, and for the Brewers, he was considered a pretty big get.

In a cruel twist of fate, Miller suffered a major injury just when he seemed to be reestablishing himself. He went down with elbow trouble in early September and underwent Tommy John surgery in October. Without much of a market, the Chicago Cubs scooped him up on a two-year contract late in the offseason, hoping that they could use him in 2027. Little did they know the reliever had other ideas. He's zoomed through his recovery, and might pitch in the majors less than 12 months after having been on Dr. Keith Meister's table.

The Case for Cubs Calling Up Shelby Miller

First and foremost, we have to forget what we remember about Shelby Miller. The "old" Shelby Miller was a starting pitcher that relied heavily on a diet of four-seam fastballs, sinkers and cutters. He would also mix in a curveball (pretty regularly) and a changeup (sparingly). He got more groundballs than flyballs. He gave up a decent amount of contact. That guy is gone; long, long gone. 

This is also not the same version of Miller whom the Dodgers and the Tigers had in their bullpens during the 2023 and 2024 season. During those years, Miller's average fastball velocity sat at 93.6 MPH. He had scrapped most of the noise around the fastball, ditching the sinker, cutter, curveball and changeup almost entirely. Instead, while he still relied on the four-seamer nearly 60% of the time, he mixed in a splitter around 20% of the time and a sweeper the rest of the time. The foundation was set for a reinvention, but his fastball velocity was keeping him back. Something had to change for him to really become a weapon. 

Last season, he rediscovered the lost electricity in his arm. His fastball sat a full two ticks higher than it had the prior two years, and sometimes touched 97 MPH. The results were fantastic: elite chase, whiff and strikeout rates, a 2.74 ERA and a 3.67 xFIP. He specifically became a deadly weapon against left-handed batters, striking out 32.4% of lefties last season. That was a whole new guy. 

That was, at least, until Miller went down with the injury that keeps pitchers up at night: a torn UCL, requiring Tommy John surgery. These operations can keep pitchers out quite some time. Just look at starting pitcher Justin Steele, who's still working back from an internal elbow brace surgery, the "younger brother" of TJ. Corbin Burnes underwent Tommy John last spring and looks like he won't pitch in 2026, either. Miller, however, has had a near-miraculous recovery and started throwing in Mesa back in July. Since then, he's rocketed from "throwing to hitters on the side" of the Complex backfields to "promoted to Triple-A Iowa" in just a matter of weeks. Best of all, the velocity hasn't gone anywhere. He's averaging 95.5 MPH so far at Triple-A. It very much looks like the player who emerged last summer survived his unhappy fall and winter. 

In just under six innings so far at Iowa, Miller has struck out 10 hitters and walked only one. He's running the kind of chase, whiff, zone, and stuff ratings you would hope for from a veteran big-leaguer just visiting the minors. His stuff grades out well, too. Everything here points to a healthy and viable reliever for a team who has been searching up and down for as much pitching as they can get. 

The Case Against Cubs Calling Up Shelby Miller

The biggest case against calling up Miller is that it's just hard to know how much you can count on him. The timeline for his recovery is miraculous. With that said, he's yet to go on back-to-back days. instead, the Cubs have cautiously given him at least a few days off in between every inning he's thrown. That's not a luxury the team would have if they tried to carry him for, say, a postseason series.

If Miller was the only reliever on the team after rosters expand that may need to be micromanaged in terms of his usage, you could probably find a way around that, especially with the added number of arms at your disposal. The problem, of course, is that the Miller's usage issues aren't in a vacuum. They have a handful of pitchers who may also be on some innings limitations. Justin Steele, Ben Brown, Edward Cabrera and Hoby Milner are all possible reinforcements who might return from injuries of their own, and the Cubs will have to be cognizant of how they use them all. Adding another arm into that mix could prove difficult and may make it impossible to keep a keen on every single inning. 

Another reason the Cubs may not call up Miller: they don't have to. Because Miller is on the 60-day IL and coming back from elbow reconstruction surgery, he gets to play by different rehab rules. Normally, a pitcher is allowed a 30-day rehab window. For Miller, that begun at the start of August. But because of the specific nature of Miller's ailment, the Cubs are granted a 60-day window. It means that the team doesn't have  to make that decision this year, like they would if he was coming back from a hamstring pull. The Cubs can, in essence, "have their cake and eat it, too" by keeping Miller in Iowa for the remainder of the season while still keeping pitchers like Aaron Civale (who's been quite good in long relief) or Caleb Thielbar for as long as they can. It's a decision that they can kick down the road to 2027, and they may be forced to do just that, simply in the name of maintaining as much depth as possible. 

Should the Cubs Call Up Shelby Miller?

The goal of the Chicago Cubs at this point is very clear: to win the last game in the postseason. This is not a team who is in for half-measures; trades like Jefferson Rojas for two players on expiring contracts (Clay Holmes and Tyrone Taylor) make that very clear. The best way for the team to achieve that goal is to ensure that their 26 best players see as much game action as possible. I believe a 100% healthy Miller is among those 26 best players. 

Miller fills a pretty obvious space in a bullpen. He's a right handed pitcher with reverse splits (due to his high splitter usage). He adds a lot of strikeouts, chase and whiff to a bullpen; all things that are quite useful. He'd allow the Cubs to move on from a struggling left-handed pitcher like Caleb Thielbar without feeling like they'd be short in the bullpen against left-handed hitters. Miller could essentially fill the role that Jacob Webb was filling early in the year and has since been vacated as he's risen to the team's defacto closer. 

But the sticking point that the Cubs' will have to wrestle with is a tricky one: how close to being 100% is Miller right now? And if he isn't 100%, at what percent is the cross-over point? The velocity suggests that his arm is feeling quite good, but his usage suggests some reservations in how often he can go. And to be fair to everyone involved; no one thought Miller would be pitching in Iowa in August, so being cautious with his usage feels entirely warranted. 

I think Miller will throw innings for the Chicago Cubs in 2026, because I don't believe the Cubs would have been as aggressive with him if they didn't think it was possible. Whether or not they call him up the moment rosters expand is another question, but it's likely that someone on the pitching staff will need an IL stint between now and October. 

This is a new, reinvented Shelby Miller, who has busted his hump to come back from TJS this year. He's had the tenacity to stick in a league that rarely wanted him, and the drive to not allow a serious elbow injury to keep him down. If you're putting together 26 men to win that last game of the playoffs, it's that kind of stubbornness you want to see in a reliever when you call upon them in tight situations.

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