The White Sox’ rotation has logged the fifth most innings in baseball, and only one other team in the game has used only five starting pitchers through more than a quarter of the schedule.

The results have obviously been mixed, but the guys have posted. They’ve been healthy and dependable, a beacon of good (read: no) injury news among a tidal wave of bad for the White Sox this season.

But the safety net for the South Side starting staff just vanished.

Davis Martin will miss the remainder of the season after undergoing Tommy John surgery, and the team’s lone confidence-inspiring depth piece is no longer at its disposal should — nay, when — the White Sox need to plug a hole in their rotation.

Martin was very good in fill-in work last season, pitching in 14 games and making nine starts. His ERA at season’s end, a less-than-sterling 4.83 mark, wasn’t reflective of his season-long quality, inflated thanks to a nine-run shelling in Game 162. He carried a 3.65 ERA into that start and had only given up more than three earned runs in two outings.

Because of it, Martin seemed a luxurious piece of pitching depth, obviously deserving of more major league work but an asset as a sixth starter behind a veteran-laden big league rotation. Given that no major league team makes it through the sport’s six-month marathon on five starters alone, it was all but guaranteed that Martin would be called on at some point, even with the White Sox experiencing good health in their rotation early.

Now, though, Martin is no longer an option.

Pedro Grifol pointed to Jesse Scholtens as the likely next man up once an opening in the rotation comes around due to injury or whatever else. Past Scholtens — who has a 3.99 ERA in seven Triple-A starts and made a couple major league relief appearances in April — Grifol said there are a few others in the minor leagues who are nearing readiness for such a fill-in assignment, if necessary, but didn’t list specific names.

That strikes as rather unexciting and perhaps even completely lacking, depending on how much of a chance you’re willing to give unproven pitchers — which Martin was a year ago, it should be noted — before rushing to judgment. But any potential for success aside, it’s true there’s practically nothing in the way of experienced starting depth lurking for the White Sox in the minor leagues.

So that’s not great.

The rotation has not been an outlier when it comes to problem areas for the White Sox’ during a 15-28 start to the campaign. Lance Lynn came into his Tuesday-night start with the highest ERA (7.51) of any qualified starting pitcher in baseball; his excellent seven-inning outing dropped it nearly a full point to 6.66. Michael Kopech has allowed a dozen home runs this season, the second highest total in the game. Mike Clevinger hasn’t exactly been bringing up the rear, but he’s failed to impress much and brought a 4.79 ERA into his start Wednesday, a mark still lower than that of Dylan Cease, who hasn’t looked like the same guy who finished second in the Cy Young vote last year.

Only Lucas Giolito has been consistently good, and that fact has prompted many fans to call for change in the starting rotation. Without Martin, though, in what form would that change arrive? No, none of this quintet seems to be going anywhere, unless forced out by injury.

Even, though, if performance is unlikely to create a need in the starting five, injury very easily could. The White Sox, for all their horrid injury luck, have experienced relatively good health the last three seasons when it comes to their starters, only Lynn’s two-month absence due to springtime knee surgery last year and Kopech’s various maladies throughout 2022 spring to mind.

Now, without Martin, it’s critical that the trend continues.

The White Sox are already taking precautions to ensure that happens. Taking advantage of Monday’s off day, they flipped Cease and Kopech in the rotation, giving Kopech an extra day of rest. According to Grifol, that had nothing to do with allowing Kopech more time to iron out any issues and everything to do with making the starters as available as possible.

“We’re going to do that with everybody at some point,” Grifol said Wednesday. “We’re just waiting for days off to be able to do that. We have five guys, and we’ve played 40-whatever games. We want to make sure when we have the opportunity to give them a day or two off they can get a little extra rest and keep them going to recover from whatever they need to recover, whether it’s they’re tired or muscle soreness, whatever, it doesn’t matter. … We’ll do it throughout the rotation.

“I just wanted (Kopech) to get an extra couple of days just to flush whatever needs to be flushed out, body-wise, and just get back going, in general. Those other guys are going to get their time, too.”

Fans might be spoiled by how swimmingly Rick Hahn’s signing of Johnny Cueto worked out last season, the veteran agreeing to a minor league deal right before the start of the regular season and coming to the rescue with a phenomenal year when Dallas Keuchel was DFA’d.

But there was no similar signing this spring, not of the same magnitude, at least. Hahn did add pitching depth, by definition, in Scholtens, Nate Fisher and A.J. Alexy. But certainly they’re not the former Cy Young candidates that Cueto was.

With Lynn on the mend last season, the White Sox could point to an opening in the rotation that Cueto could help fill. They couldn’t this winter or spring, not with Cease, Lynn, Giolito, Kopech and the newly signed Clevinger soaking up all five spots. To get the kinds of pitchers that make fans excited to sign up with no guarantee of being anything but rotation depth or a bullpen arm would seem a challenge.

Not that it’s an excuse, however. And if the White Sox’ rotation breaks down without Martin to step in, that’ll be the organization failing to prep enough usable replacements, be that through internal development or external acquisition.

Though the White Sox are far from finished trying to resurrect their 2023 campaign — “it’s not late” was Eloy Jiménez’s fresh spin on the “it’s early” line fans are sick of — Martin’s surgery also brings up long-term questions. With Giolito slated for free agency after this season and the White Sox holding $30 million worth of contract options on Lynn and Clevinger, they could be in the market for a lot of starting pitching come the winter. And if they were counting on Martin being a part of their 2024 starting-pitching plans, well, they might be in the market for more than they expected.

But the bigger concern for the White Sox is, of course, in the immediate. Not only is Martin not going to answer fans’ more unrealistic prayers for a performance-related starting-pitching shake up, he also won’t be able to answer any more realistic need that might arise due to injury.

Pending an out-of-nowhere emergence of someone like Scholtens — which has obvious precedent in what Martin did last year — the White Sox’ rotation is playing the remainder of the season without a net. That’s not an enviable position to be in, considering the obvious realities of a major league season and the microscopic margin for error the team has as it attempts to ascend from its sub-.500 standing.