Boston starter Josh Beckett fires a pitch to home plate in the first inning during Arizona’s 2-1 victory last night.

The Providence Journal / Mary Murphy

BOSTON — The scoreless duel got away from Boston starter Josh Beckett in the seventh.

While the right-hander was at fault for a leadoff walk, the run-producing double by Chris Young was of the tip-your-cap variety. And the second run was the result of an educated gamble by Arizona manager Bob Melvin, not to mention a momentary bobble.

Young must have been looking away for a fastball, but he went out and hooked a good pitch, a knee-high fastball on the outside corner, off the wall for an RBI double, giving Arizona a 1-0 lead.

That put runners at second and third with one out. Catcher Chris Snyder, hitting eighth in the Diamondbacks’ lineup, was at the plate. Beckett attacked the right-handed hitter with curveballs. He threw three in a row — but missed with all three, running the count to 3 and 0.

Most of the time, a manager will have a hitter take the 3-and-0 pitch, especially a number-eight hitter.

In this instance, though, Melvin knew a fastball would be coming after three straight curveball misses. Every big-league hitter can hit a fastball, especially if he’s certain one is coming. So he had third-base coach Chip Hale give Snyder the hit-away sign. Beckett threw a 96-mph fastball on the outer half of the plate.

Snyder didn’t get a good piece of it. In fact, he broke his bat. The ball had a lot of spin as it approached first baseman Brandon Moss, making his big-league debut at the position, having taken over in the fifth for Kevin Youkilis after an infield drill mishap left Youkilis with a bruise under his right eye.

The Diamondbacks also had instructed the runners to be on the move on contact. So as soon as the ball hit Snyder’s bat, the runners took off. If Moss had fielded the ball cleanly, he would have had a play on Mark Reynolds at the plate, though it was no certain out.

Moss, though, bobbled the ball. Reynolds then scored an important insurance run.

skrasner@projo.com