WORCESTER — It was simply a matter of time.

Until Caleb Allen settled into a groove. Until the bats came to life. Until the Oakmont Regional baseball team found its footing and showcased just how cool and collected it had been all season.

Top-seeded Oakmont rallied from a 1-0 deficit in the first, doing its damage in the middle innings en route to a 3-1 victory over No. 2 St. Mary’s of Lynn at Polar Park to successfully defend its Division 3 championship.

“(The championship) is still ours. It’s a storybook ending for us,” Oakmont head coach Tim Caouette said. “Once we won last year, we wanted to come back and do it again and it all played out the way we hoped it would. We wanted Caleb to have the ball at Polar Park to defend that title and he did.”

Allen, a flame-throwing senior, scattered three hits and a walk over his seven innings, striking out 10 for Oakmont, which closes the season with a 22-3 record. He gave up a pair of singles and a walk in the first, leading to a run, but settled in and shut down St. Mary’s bats.

“I was feeling great after the first. Obviously, I wasn’t feeling great in the first, giving up a run early, but I trusted my team and knew we’d get a couple runs,” Allen said. “The game plan was to pound away in the zone because we thought they wouldn’t be able to hit it and once I started hitting my spots, our scouting was perfect.

“I just needed to settle in and then everything was great.”

The righthander was relegated to shortstop duty during last year’s championship game, having pitched in the semifinals.

“I’ve been thinking about this game since last season,” he said. “And it’s been on my mind since we won in the semifinals (on Tuesday).”

Trailing 1-0, the Spartans pulled even in the fourth. Sam Curtis (3-for-3, RBI, run) singled with one out before stealing second. He came in to score on a single by Allen to knot the game at 1.

The following inning, Oakmont took the lead.

Jake O’Day singled off Josh Doney (6 IP, 6 H, 2 BB, 7 K) with one out and was followed by a walk to J.J. Walker. After Ty Curtis singled to load the bases, Johnny Losordo hit a sac fly to center to score O’Day and break the tie.

Sam Curtis then hustled to reach on an infield single, scoring Walker and giving the Spartans a two-run lead.

“I knew he was going to pound the outside with the fastball and he had good off-speed,” Sam Curtis said of Doney. “I was just sitting on the fastball in each at-bat. I was feeling confident up there.”

Sam Curtis also had the defensive play of the day, diving behind second base to stop a bounding ball hit by Rowan Merryman and throwing the St. Mary’s freshman out from his backside in the sixth inning.

St. Mary’s (20-4) got on the board early and put the pressure on Oakmont.

Michael DeMaino led off with a bloop single to left before Jaiden Driscoll walked. Doney helped his own cause with a single to left that plated DeMaino and gave the second seed a 1-0 lead before an out had been recorded.

Oakmont’s Jake O’Day celebrates after reaching home plate during the MIAA Division 3 state baseball title game. (Libby O’Neill/Boston Herald)