Clay Buchholz is here to say he’s sorry.

It isn’t so much that the senior member of the Red Sox rotation gave up 10 runs in 3-1⁄3 innings Sunday night at Yankee Stadium, statistically the worst of his 151 career starts. Bad as that was — and make no mistake, it was atrocious — it’s also a fact of life that every big league pitcher is going to throw the occasional stinker.

No, what has Buchholz feeling contrite, even embarrassed, is the fact that he became so emotionally unglued by that beating five nights ago in New York that he forgot to do the most basic part of his job, the one thing that should come easier than any other whenever he scales a mound.

He forgot to make an effort.

“There’s no excuse for it,” Buchholz said Wednesday in a private moment amid the pregame calm at Fenway Park before a matinee series finale against the Washington Nationals. “I was pissed off and things were happening really quick, but no, there’s no excuse for that. I told the staff it wouldn’t happen again.”

It looked bad because it was bad, Buchholz watching from the mound rather than backing up home plate as slow-footed Yankees catcher Brian McCann scored from first base on a bases-loaded double by Alex Rodriguez in the first inning. Three innings later, Buchholz didn’t bother backing up third base as Didi Gregorius advanced from first on a Jacoby Ellsbury single.

Not exactly the example you want from the purported leader of your pitching staff.

Buchholz didn’t have sinister intentions. He wasn’t trying to show up his teammates, which likely explains why manager John Farrell passed on a public postgame scolding, though he did note “there’s responsibilities to the game situation and that includes backing up bases. The game doesn’t stop (when you’re losing).” And Buchholz copped to making a “mistake” but inexplicably brushed off the whole thing by saying he “felt like they were going to score regardless of a good throw or not.”

But Buchholz said he and Farrell spoke privately, at which time he accepted blame for shirking his defensive duties and vowed not to make it a habit.

“I’m a lot better player fundamentally than that,” Buchholz said. “I just let the game get to me the way it was going. That’s my responsibility to do the little things in the game regardless of how the game’s going, and I didn’t do it. It won’t happen again.”

If only he could make the same guarantee about his erratic pitching, his first two starts of the season serving as a microcosm of the past nine years.

Buchholz came out blazing, shutting out the lowly Phillies for seven innings on Opening Day in Philadelphia just as he no-hit the Baltimore Orioles in his second career start in 2007 at Fenway Park. But trouble seems to lurk around every corner he turns, whether it’s back and shoulder injuries that sidelined him for months at a time in 2011 and 2013 or a 10-run rout by the Yankees, who have dished out five of the 14 worst poundings of his career and against whom he has a 6.38 ERA in 16 starts.

Let’s dispense, then, with the notion that the 30-year-old right-hander will suddenly morph into a dependable No. 1 starter. After all these years, the Red Sox surely can’t believe he has it in him either.

Instead, let’s recalibrate our expectations. If Buchholz can stay healthy and achieve some measure of consistency — no guarantee on either count — there’s no reason he can’t be an effective No. 2-3 starter, which in this pitching market would still make him well worth his $13 million team option for next season.

“If I had to say at the beginning of the season that I’m just going to give up three runs every game, then I would give up three runs every game rather than going eight innings giving up none and then going four innings giving up five, six or seven the next time out,” Buchholz said. “That’s the name of the game, being consistent. You definitely don’t want the extreme sides of it.”

Buchholz’ search for consistency will continue tomorrow against the Orioles. He was encouraged by his between-starts bullpen session Wednesday, believing he identified the root of his problems against the Yanks.

“I got into a predictable mix where I was throwing fastball first pitch and then going straight to offspeed,” Buchholz said. “If I could go back and do it all over again, I probably would have done a few things differently.”

Chief among them: Giving a better effort.

For not doing so, Buchholz apologizes. The Sox trust it won’t happen again, even if they would be foolish to trust that Buchholz will ever be the consistently dominant No. 1 starter they need.