Labor Day weekend. The unofficial end of summer. Of course, if your summers are measured by where the Red Sox stand in proximity to first place, this one was over a long time ago.

The Red Sox wrapped up the month of August with a 3-0 win over the Tampa Bay Rays on Sunday at Tropicana Field. Pitcher Clay Buchholz provided a reminder of his talent with a three-hit shutout.

Buchholz has the best stuff on the staff. Most talent evaluators thought that was true before the Sox traded away four-fifths of the rotation in July. Stuff has never been the issue for Buchholz.

The question is always whether he can be durable enough to put that talent on display for 30 starts, whether he has the toughness to gut it out through a full season.

“He was in complete command for nine innings,” Red Sox Manager John Farrell told reporters after Sunday’s game. “Outstanding effort. He’s got such an ability to manipulate the baseball with some late action.”

We’ve seen that ability. In 2010, Buchholz posted a 2.33 ERA and finished sixth in the AL Cy Young voting. Last season he was the best pitcher in baseball for the first 10 weeks of the season, posting a 12-1 record with a 1.74 ERA.

That season was cut short by an injury. And he hasn’t been the same since.

Yet Buchholz insists he is fine.

“I don’t feel any different physically,” Buchholz told reporters Sunday. “That was the one thing I could look back at this year, it had nothing to do with me physically. It was more just things didn’t happen for me the way I planned for them to happen and the way I wanted them to happen.”

Whatever that means.

Here’s what happened in Buchholz’s last two starts: He pitched 171/3 innings, allowed three runs (all of which scored after he left the game in Toronto on Aug. 28) and recorded 26 ground-ball outs to just 11 fly-ball outs.

“I know he’d been hurt,” Rays Manager Joe Maddon told reporters after Sunday’s game. “He gets well, and all of a sudden he’s looking like he did a couple years ago.”

It’s tough to figure out where Buchholz fits into the Red Sox future plans. They’ve got him under control for the next three seasons, with a pair of team options that could keep him here through 2017.

There’s no doubt he’s the team’s current No. 1 starter. Yet it’s hard to think of him being the opening-day starter next season.

We’ve heard the Red Sox will look for an “ace” aggressively this offseason, both through trades and free agency, a sure sign that they don’t think they have one.

Bottom line is you just can’t depend on Buchholz to anchor your rotation. The number of frustrating setbacks in his career shows us that.

Yet the dazzling performance we saw Sunday was a reminder that he will be an important part of a rebuilt rotation next season.

Even if he isn’t sitting at the top of it.

Tom Caron is the studio host for Red Sox broadcast on NESN. His column appears in the Portland Press Herald on Tuesdays.