BOSTON — Let the second-guessing begin.

Danny Ainge and the Boston Celtics chose to roll the dice last night and bypassed a high pick in one of the deepest NBA drafts in years and instead traded for seven-time all-star Ray Allen.

The Celts shipped the fifth pick in the draft along with high-priced guard Wally Szczerbiak and Delonte West to Seattle for Allen and a second-round pick. The deal answers the prayers of team leader Paul Pierce and coach Doc Rivers for another veteran presence in Boston’s lineup. Rivers can now look forward to a high-scoring triumvirate of Pierce and Allen on the wings and young big man Al Jefferson inside.

“We think Ray Allen is a great player and has a lot of basketball left in him,” said Ainge. “It’s really hard to acquire all-star-caliber players. We couldn’t be more thrilled. He’s going to be a fantastic addition to our team. He gives us a chance to compete in the Eastern Conference.”

After a week of hearing reports that the Celtics were shopping their pick and trying to bring Kevin Garnett, Jermaine O’Neal or Shawn Marion to town, Allen’s name surfaced early yesterday. The Sonics were already huge winners in the draft after coming up huge in the lottery by landing Texas All-American Kevin Durant with the second pick. Now they’ve pushed Allen’s contract —which runs for three years and $52 million — to Boston and added Szczerbiak, West and Georgetown forward Jeff Green to a roster that also includes Rashard Lewis.

Although Ainge wouldn’t speculate on future deals, the Celtics can’t be counted out in the Garnett sweepstakes. After trying to peddle his superstar for weeks, Minnesota general manager Kevin McHale couldn’t swing any draft night deal and may not be able to welcome him back for the final two years on his contract. Boston remains very interested, however, and still holds the ammunition to offer McHale in Jefferson, future first-round draft picks and the $11.6-million contract of center Theo Ratliff, which expires after next season.

“We’re always looking to do deals to make us better,” is all Ainge would say when asked about Garnett.

A team featuring Pierce, Allen and Garnett would clearly excite Celtics fans everywhere and elevate the team into the NBA’s upper echelon. The trio would also cost the team’s owners $54 million next season. Without a trade for a big man like Garnett, the Celts would remain woefully thin up front and very weak defensively.

Allen, who turns 32 years old in July, is coming off a productive, but injury-riddled, season. He averaged a career-best 26.4 points last season but was limited to 55 games due to injuries with his feet. Even so, he scored a career-high 54 points on Jan. 12 against Utah and scored 30 or more points 18 times. His 4.5 rebounds and 4.1 assists per game were his best since the 2003-04 season.

Allen had surgery in April on both of his ankles to alleviate pain caused by bone spurs. He wore protective boots for nearly two months but they were removed in early June. He’s been working out in a pool and riding a stationary bike, but not cleared to run.

“I’m not able to do anything. I’ve slowed down a lot ... especially in the summertime when you want to do so much,” Allen told the Associated Press in early June. “But my body is feeling great.”

Asked about Allen’s condition, Ainge said the Celts began talks with Seattle more than a week ago and checked his health. “We think he’s ready to go. We think he’ll be ready to go by training camp, if not by August.”

At least one media report claimed that Seattle nearly backed out of the deal after failing to get the Celtics to include point guard Rajon Rondo instead of West. Ainge brought up center Robert Swift, one of his long-time favorites, but the Sonics wouldn’t go there, according to SI.com. Ainge said that an hour before the draft he thought the deal was dead, but “we got closer and closer together.”

“Boston really pursued this. What started as a smaller conversation became fulfilled. Their pursuit was impeccable,” new Sonics general manager Sam Presti told the Associated Press.

While the Celtics take on Allen’s maximum contract, they’re freed of the two-year, $26.6-million contract they owed Szczerbiak.

Ainge said adding Allen will help take advantage of Pierce’s skills. “We want to maximize his career and surround him with more veterans and more talent. That’s something we’ve been trying to accomplish,” Ainge said.

Rivers called Allen “a top-25 player in the league ” who will make the entire team better.

As part of the deal, the Celtics made Seattle include its second-round pick, number 35. That gave Boston the second and fifth picks of the round, and Boston chose Southern California’s Gabe Pruitt with the 32nd pick and LSU’s Glen “Big Baby” Davis at 35. The 6-foot-4 Pruitt averaged 12.5 points and 4.2 assists for the Trojans last season, leading the team with 47 steals. He’s not a pure point guard, but Ainge has him slotted at that spot alongside Rajon Rondo and Sebastian Telfair.

Davis combined with Tyrus Thomas to lead LSU to the Final Four in 2006, but the Tigers missed the NCAAs this year. Davis led the SEC in rebounding but has always battled a weight problem.

kmcnamar@projo.com