A six-man rotation seems attractive on paper, but not on the mound

Boston Red Sox starter Lucas Giolito contends that a six-man rotation is “not really conducive to what we’re trying to do to help the team.” (X via Lucas Giolito)

By Chad Jennings / The Athletic

Even before his ace went on the injured list, when he had six legitimate starters, a progressive front office and a mind open to innovative solutions, the Tampa Bay Rays’ pitching coach, Kyle Snyder, never seriously considered using a six-man rotation. He is intrigued by the concept, but Snyder just can’t make the numbers work. He’s not ready to volunteer for that particular pitching experiment.

“But let us carry 14 pitchers,” Snyder said, “and I’ll put my hand in the air.”

By some standards, the six-man rotation should be having its moment. Every team in baseball is desperate to keep its pitchers healthy. Statistical and biomechanical markers tell teams that extra rest can help performance: Arm slots stay a little more consistent. Velocity doesn’t dip quite as much. The outs come just a little bit easier. General managers are stockpiling depth, managers are enforcing pitch limits and complete games are relics of a bygone era. Everyone, it seems, is trying to find a way to improve the state of starting pitching.

But not one major league team opened this season with a six-man rotation. Plenty were asked about it in spring training, and some said they were considering it, but even those that had more than enough starters either dismissed the idea out of hand or ultimately settled on a five-man rotation out of camp.

Despite the devastating impact of arm injuries, leaguewide concerns about workload and the aesthetic desire for starting pitchers to work deeper into games, a six-man rotation has been, at best, a short-term fix.

“Ultimately we’re solving for winning games, and not five starters or six starters,” the Boston Red Sox’s chief baseball officer, Craig Breslow, said. “I think the knee-jerk reaction is, when you engage in risky behaviors, one way to mitigate risk is to do them less. But we have to think about the burden it places on others.”

Some of the burden is a byproduct of roster limits. Teams can carry no more than 13 pitchers, meaning a sixth starter would come at the expense of an eighth reliever, and teams are hesitant to make that concession. The burden would fall on that sixth starter to earn his keep, on every other starter to work deeper into games, on each reliever to pitch more often, on each manager to better allocate workload, and on each front office to maintain depth and flexibility.

And, there’s no guarantee a six-man rotation would solve the underlying issues of starting pitchers getting hurt or exiting games in the fifth inning.

“I don’t think you’re going to talk to many starting pitchers who are in favor of a six-man rotation,” Red Sox starter Lucas Giolito said. “It’s not really conducive to what we’re trying to do to help the team.”

The New York Yankees had a six-man rotation for a while in 1973. Manager Billy Martin used one with the Texas Rangers in 1975, then brought it back to the Yankees in 1985. The Cleveland Indians had one in 1991, the New York Mets tried it in 1998, and the St. Louis Cardinals had six starters down the stretch in 2007. None of these were season-long experiments.

Among the many roadblocks mentioned by pitching coaches, managers and executives, one is especially straightforward: A six-man rotation takes starts away from an ace. If Tarik Skubal, Paul Skenes and Zack Wheeler are capable of 33 starts, why would the Detroit Tigers, the Pittsburgh Pirates or the Philadelphia Phillies want them to make only 27?

Other barriers fit into the category of limited supply. It’s hard enough to find five capable starters. Imagine every team trying to find six. And even if they could, many of those sixth starters would otherwise have been long relievers. Rotation depth would grow thin in a hurry, and bullpens might be depleted even faster with seven relievers doing the work of eight.

“It comes back to that ripple,” Snyder said.

The Los Angeles Dodgers are the team most likely to implement and stick with a six-man rotation, but that’s largely because they have a player who defies roster constraints. When two-way phenomenon Shohei Ohtani returns to the mound, he will be a starting pitcher, but he’ll still count as a position player. The Dodgers will be able to carry Ohtani, plus another five starters, plus a full complement of eight relievers, without violating roster limits. But a six-man rotation without Ohtani?

“I think it’s doable,” the Dodgers’ pitching coach, Mark Prior, said in an offseason interview with the “Dodgers Territory” podcast. “The biggest issue is, do you have the depth to be able to do that?”

When the Dodgers used a six-man rotation for two turns last June, they added five fresh arms in a span of six days to help get through it. The Red Sox, the Mets and the Cardinals are among the teams that have acknowledged plans for a six-man rotation during especially dense chunks of the schedule, but those teams have multiple relievers with options, meaning they can — in theory — rotate fresh arms in and out of the minors to deal with workload challenges.

Regular rest is a misnomer because pitching every fifth day is actually not all that common. Snyder said that roughly 35% of starts fall on Day 5. Bush said he’d never done the math, but he generally assumes that three out of five starts will come with an extra day of rest.

One example: From May 29 to July 9, the Red Sox could go more than a month needing a starter on normal rest only five times, and each of those starts would fall on a different member of the rotation. It’s one reason Arizona Diamondbacks manager Torey Lovullo, even when his team had six veteran starters in spring training, dismissed the idea of a six-man rotation to open the season.

“It wouldn’t be a pure five-day thing,” Lovullo said. “It might be a little bit of a challenge to get guys the amount of work that they need to go out and perform.”

While there are biomechanical markers showing that rest can help a pitcher perform, there is also a sense that too many days off can be detrimental. And even when extra rest helps with performance, “it’s a dotted line at best between that and injury risk,” Breslow said.

If a six-man rotation were proven to keep pitchers healthy, teams would be doing it already. But pitchers might alter their training to get more out of fewer starts, and asking them to pitch deeper into games could be risky. Some coaches, like Snyder, are intrigued by the potential for better health outcomes, but others are unconvinced that fewer starts will mean fewer MRIs.

“I don’t think four days of rest vs. five days of rest makes that big a difference in the grand scheme of things,” Giolito said. “I think the difference maker is guys doing velocity programs and throwing as hard as humanly possible every single pitch, ripping breaking balls as hard as they possibly can. The human body just can’t withstand that.”

Maybe the six-man rotation eventually will have its moment. Maybe it will not. But the search for better outcomes will continue.

“These are the conversations that need to be had on the daily,” Snyder said. “Because I want the game to be more watchable, and I want to keep all of our pitchers healthy.”