BOSTON — There’s no way to predict how many wins promising right-hander Clay Buchholz is going to rack up in his career with Boston.

But last night, in throwinga no-hitter in just his second start in the majors, Buchholz, who recently turned 23, showed that he already has not only the stuff to be a star, but also impressive composure on the big stage.

There were three early illustrations of his poise.

Buchholz’s first three pitches to Kevin Millar leading off the second inning were out of the strike zone. So the count was 3 and 0. Young pitchers tend to have control issues when first called up.

Buchholz, though, calmly fired in a get-it-over fastball that Millar took for a strike. Then he threw two more fastballs. Millar swung and missed each one for a strikeout.

Another moment. In the third, Brian Roberts, batting with two out and none on, tried to drop a bunt for a hit. Roberts deadened the ball on the grass toward first base and took off down the line, running on the inside part of the baseline.

Buchholz got off the mound in a hurry. But he didn’t panic, as some young pitchers might have done in this situation. He picked up the ball and, under control, fired a strike to first baseman Kevin Youkilis, keeping the ball on the inside of the baseline, making sure he didn’t hit Roberts.

Still another moment.

Roberts was on first base after being issued a leadoff walk in the sixth. Buchholz caught him sleeping, threw over and picked off Roberts, who was just standing close to the bag, not even having taken a lead yet. Buchholz made a perfect throw.

Those indications that he’s a solid candidate — if not a lock — for a spot in the rotation next spring go hand-in-hand with his stuff, which is impressive. Buchholz has three pitches he has developed confidence in, as shown last night.

Two at-bats stood out in that regard.

In the first inning, his first three pitches to Corey Patterson were fastball (92 mph), changeup (80) and curveball (76). In the third, his first three pitches to Jay Payton were fastball (91), curveball (77) and changeup (80).

Even if they aren’t thrown for strikes — and a couple of them missed — the seed gets planted in the hitter’s mind that he has three pitches to look for when he’s in the box. That’s an unsettling proposition because the hitter knows Buchholz has confidence in all three of them — and catcher Jason Varitek has confidence calling for each one of them — so he doesn’t know which pitch to expect.

Buchholz is by no means perfect yet, of course. Young pitchers will have their bouts of inconsistency, even talented ones. Buchholz, for instance, walked the first two batters in the fifth, but after a visit from pitching coach John Farrell he settled down and stranded the base runners, keeping his no-hitter intact.

To say he was impressive last night, and offers great promise, is an understatement.

Little things add up

Anatomy of a big inning. It’s the little things that lead to good things, as happened in Boston’s three-run third-inning flurry that produced a 4-0 lead.

With two outs and none on, Brandon Moss scalded a low liner to Roberts, the Orioles’ second baseman. Roberts either didn’t have time to take a half-step to get in front of the ball, or didn’t think he had to. Anyway, he missed it. The ball may have dipped on him, but the bottom line is he didn’t make the catch as he should have, which would have ended the inning. Instead Moss was at first base, credited with a single.

Next up was Julio Lugo. He was 0 for 14 and just 2 for his last 23. Lugo dropped down a perfect bunt down the third-base line for a single.

Then Dustin Pedroia slapped a grounder in the shortstop hole. And, in one of the few cases where sliding into first base makes sense, Pedroia could see the throw was going to be wide, to the home-plate side of the baseline.

Suddenly the Sox had the bases loaded and Big Papi delivered a three-run double high off the fence in left-center.

skrasner@projo.com