The Red Sox have a starting pitching problem, but how big of a problem?

Chris Sale has made six starts since he was reinstated from the injured list on Aug. 11, and has completed five innings just twice.Matthew J. Lee/Globe Staff

The Red Sox have a starting pitching problem.

Kutter Crawford’s inability to get through the fifth inning in Tuesday night’s loss to the Yankees was the latest example of just how much this rotation has struggled.

Crawford made it through the first four innings scoreless. He registered the first two outs of the fifth with the Red Sox holding a 1-0 lead. But a walk, stolen base, and a 10-pitch at-bat by Estevan Florial, which resulted in an RBI single, ended Crawford’s night.

It was another reminder of what has plagued this rotation: It just can’t pitch deep into games.

Entering Wednesday, Red Sox starters had pitched just 236⅓ innings since the All-Star break, the second-fewest in the majors.

The Red Sox banked on getting Chris Sale and Tanner Houck back, but both were on pitch limits and have underperformed. Sale has made six starts since he was reinstated from the injured list on Aug. 11. The Sox are 13-17 overall in that time. Sale, meanwhile, has completed five innings just twice in those six starts.

Chris Sale was supposed to reinvigorate the Red Sox rotation with his return from injury along with Tanner Houck, but innings limits and underwhelming play have kept both from making a big impact.John Tlumacki/Globe Staff

“If you look around the league, and you look at Toronto, those guys, most of them are going to get 200 innings,” said Red Sox manager Alex Cora. That’s the difference between this year and 2021. Everybody talks about the magic run in 2021. It wasn’t that magical run. It was just a good team with solid starters that went deep into games. It was 32 starts from [Nate Eovaldi], 31 starts [from Eduardo Rodriguez], and 30 starts from [Nick] Pivetta. Martin Perez and Garrett Richards, they were doing their part, they [each] had 22.

“Then we had Tanner coming in and doing his thing for a while there. So, I think everybody talks about the bullpen, but the first six innings are very important because then you don’t tax the bullpen, and that’s something that we ran into during that 16-game stretch recently. We weren’t going deep enough and we paid the price.”

In 2021, with the exception of Perez, and Houck (a spot starter), each Red Sox starter tossed at least 136⅔ innings. Eovaldi led the way with 182⅓. Rodriguez was second with 157⅔, followed by Pivetta with 155.

Brayan Bello leads the way for the Red Sox in 2023 with 25 starts and 142 innings. After that, excluding Pivetta (who has bounced between the bullpen and rotation), Crawford is next with 112 innings.

That’s a concern for the Red Sox. Not just this year, but in the years to come.

“If I knew the issue we would fix it,” said Cora. “It’s just one of those that hopefully we can figure out. These guys are learning, too. Some of these guys are learning at the big league level. It’s not easy. You look at Toronto, experience guys. Tampa with [Tyler] Glasnow and all those guys. They’re learning. They have to mature. Hopefully next year, with all the experience that they had this year, we can get to that next level.”

Jansen on COVID injured list

The Red Sox placed closer Kenley Jansen on the COVID-related injured list on Wednesday and recalled lefthander Brandon Walter from Triple A Worcester. Jansen left Tuesday night’s game in the top of the ninth inning because of what the team called illness and fatigue . . . Corey Kluber (shoulder) pitched 2⅔ scoreless innings for Worcester on Tuesday, yielding two hits without a walk. It is still to be determined what’s next for the righthander.