Clay Buchholz, trying to pick a Rays runner off first base during a game in May, faced a tight strike zone last night in Pawtucket.

AP / Charles Krupa

PAWTUCKET — Clay Buchholz was sent down to Pawtucket from Boston for a couple of reasons.

The Red Sox wanted him to alter his arm slot. They wanted him to work on the command of his fastball. And, in an effort to become sharper with his fastball location, they wanted him to throw the pitch more instead of relying on his devastating changeup and knee-buckling curveball.

The Sox have confidence that the rookie right-hander, who authored a no-hitter in his second big-league start last fall, will be a very good pitcher in the majors. It’s all about having Buchholz, who will turn 24 next month, fine-tune a few things before returning to Boston.

That includes dealing with whatever adversity might crop up in a game, such as a tight strike zone from the plate umpire.

Last night, in Pawtucket’s 5-2 loss to the Lehigh Valley IronPigs at McCoy Stadium, Buchholz showed a bit of frustration when plate umpire Pete Pedersen didn’t give him a few calls.

The next thing Buchholz knew, Mike Cervenak pulled a hanging breaking ball for a run-scoring double in the third inning, and the next batter, Andy Tracy, clouted a three-run homer to left-center on a fat 93-mph fastball. Those hits turned a 2-0 Pawtucket lead into a 4-2 deficit.

Buchholz, who had been 4-0 with a 0.40 earned-run average in his last four starts, made it through five innings. He threw 88 pitches, hitting the organization’s goal of 60 percent fastballs (he threw 54, 61 percent), and wound up allowing five runs on six hits, including Cervenak’s opposite-field RBI single in the fifth.

“It was OK,” said Pawtucket manager Ron Johnson, assessing Buchholz’s performance.

Buchholz, meanwhile, said he felt fine, but also admitted that Pedersen’s strike zone frustrated him.

“There were a couple of pitches that weren’t called,” said Buchholz. “He squeezed both teams. It was a tight strike zone. When I’d throw a pitch I thought was a strike and didn’t get that pitch, I’d be behind in the count.

“There were some borderline pitches not getting called that you’re used to having called and that leads to things. I guess you have to roll with the punches sometimes and hang with ’em,” said Buchholz.

That was pretty much the message imparted by pitching coach Rich Sauveur, who trotted out to the mound with the count 2-and-0 on Tracy in the third inning.

“He picked up on a few antics,” said Buchholz of Sauveur, who could tell his pitcher was frustrated with the umpire.

Three pitches later, though, Tracy launched his homer and the PawSox were losing.

Johnson, though, hopes Buchholz can use the experience as a positive because along the way, while Buchholz has unlimited potential, he is going to run into umpires whose strike zones are tight and the pitcher has to learn to find a way to succeed.

“There were some pitches that could have gone the other way, and it might have made a difference in outcomes. I’m not making excuses for him. I’ll have to look at the video, but I’m not bashing anyone here,” said Johnson.

“This game’s easy when things are going real well,” said Johnson. “It’s a test when things don’t go your way. That’s why we’re here. That’s why we have this level, to get experience in these situations and learn to deal with them.”

skrasner@projo.com