Boston hasn't shown signs of stopping the trend in its final series before the All-Star break.
Josh Beckett allowed five runs in the first frame on Friday in the series opener against New York. In the first game of a doubleheader on Saturday, Franklin Morales surrendered four. The Sox lost both games.
"It's certainly not on purpose or by design," McClure said.
Entering Saturday's nightcap, Red Sox starters had allowed at least one run in the first inning in 10 of the last 12 games at Fenway Park dating back to June 10. Boston went 6-4 in those 10 contests, thanks in large part to a high-powered offense.
So what's the solution?
"If there was a solution, it would be solved," said manager Bobby Valentine. "Bob McClure is down there warming them up and bringing them in, and they have a game plan, and it just seems like a lot of guys have struggled in the first inning."
Is preparation the root of the first-inning issues?
"That's not the problem," McClure said. "The problem is missed location. It's not the preparation, it's maybe being too careful. I can't pinpoint it right now. Maybe trying too hard. Who knows? It happens sometimes."
In the last two games, Beckett and Morales failed to establish their secondary pitches in the first inning, and that was part of the problem.
"Sometimes you have to pitch backwards," McClure said. "That's one way to kind of solve it, be a little more aggressive in the zone, getting ahead in the count."
This isn't the first time Valentine has dealt with starters who continually struggle in the first inning, though.
"I had Nolan Ryan for years, and his first inning was always a problem," said Valentine, referring to the four seasons he managed the Hall of Famer with the Rangers from 1989-92. "I don't know if I ever corrected it or figured out a solution for it. Sometimes it just happens, I don't know. I'd rather it not."