He signed his first professional contract over nine years ago.

“It’s gone pretty quick,” Stefan Welch said.

And Welch, a corner infielder from Alice Springs, Australia, is putting up the best numbers of his career.

Welch, 25, served as designated hitter for the Portland Sea Dogs on Saturday. He reached base five times, including a double and two singles, as Portland topped the New Britain Rock Cats 10-4 at Hadlock Field.

When Welch was acquired from the Pirates last June, he was struggling in Double-A. The Red Sox sent him to advanced Class A Salem, where he batted a career-best .292.

In Portland, Welch is batting .409. He has seven RBI, including five in Friday night’s win.

Those are heady numbers. Welch would rather not try to explain how he’s doing it.

“I’m not sure,” he said. “Just having a lot of fun. Got a great group of guys to play with.”

Welch loves baseball, playing it almost year-round, in the States and then back home in Australia in the offseason. He was initially signed at the age of 16 with the New York Mets, although he didn’t start playing in the U.S. until he was 18 in 2007.

Welch never got out of Class A ball with the Mets and signed with Pittsburgh in 2012. The next year he was batting .149 for Altoona when he landed with the Red Sox, and with Billy McMillon’s Salem club.

“I would label him a professional hitter,” said McMillon, now skippering the Sea Dogs. “He’s swinging with a lot of confidence right now.”

Many Sea Dogs were swinging with a purpose Saturday, collecting 14 hits in the rout.

Second baseman Mookie Betts went 2 for 4 with two RBI, while raising his average to .469.

Shannon Wilkerson and Carlos Rivero also recorded two hits apiece.

Portland trailed New Britain 4-3 until Rock Cats starter Matt Summers left after five innings. The Sea Dogs roughed up reliever Adrian Salcedo for six runs on four hits, a walk and a hit batter. He left with only one out recorded in the sixth inning.

The lead was plenty for Sea Dogs starter Mike Augliera (1-1). Augliera is a control pitcher (85 pitches/63 strikes) who cruised until New Britain broke through for four runs in the third.

“A couple of pitches were up and they did a good job of hitting,” Augliera said.

But Augliera retired 14 of the last 17 batters he faced, lasting seven innings.

“We can always count on him keeping us in the game, going deep into games,” McMillon said. “He has nothing overpowering but seems to put a little something on the ball to keep guys off balance.”

Said catcher Blake Swihart: “He’s got sink and he locates his pitches,” which include a fastball, slider and change-up.

Matty Ott and Michael Olmsted each pitched a perfect inning of relief. Olmsted’s ERA remains 0.00 after three outings (four strikeouts in 31/3 innings).

NOTES: Michael Brenly, who put Portland ahead with a two-run single in the sixth, played first base for only the 13th time in his seven-year pro career. He’s a catcher but played first a lot in spring training “so I didn’t feel so uncomfortable,” he said … The announced paid attendance was 4,022.

Kevin Thomas can be reached at 791-6411 or at:

kthomas@pressherald.com

Twitter: ClearTheBases