Danny Ainge never envisioned being able to draft Jared Sullinger. He didn’t think he would get him when Sullinger was dominating the competition in Ohio as a high school student. Ainge didn’t think he would get him when he watched Sullinger take Ohio State to the Final Four on the Celtics’ home court during the NCAA Tournament. Ainge didn’t even think he would be able to take him when the draft began on Thursday.

But as events unfolded and it looked like Sullinger would be available, the Celtics didn’t bother looking back on his two-time All-American resume or the 17 points and 10 rebounds per game he posted in each of his two years at Ohio State. Instead they checked his medical records.

Sullinger has a back problem that was flagged at the Chicago pre-draft combine. The news sent him tumbling out of the lottery and into the nether world of the falling prospect. He fell all the way into the Celtics’ laps with the 21st pick and that’s when Ainge stepped in and made the call.

“When the day started, I did not think he would be there at 21. We’re fortunate to get him,” Ainge said. “We were concerned and we did our research on the back issues and felt comfortable, but there are some issues there. Our medical staff thinks that short term and long term there may be some maintenance issues with the back. Doc Rivers played with a herniated disk for 13 years. So it may need surgery at some point, it may not.”

Ainge later clarified that he had no idea if Sullinger would need surgery, but it’s clearly a concern. Also concerning is the notion that even at 6-foot-9, Sullinger sometimes struggled against bigger defenders, who he will see every night in the NBA.

“Length is an issue,” Ainge said. “There were a lot of these same kind of issues with Glen Davis when he came in, but they just find a way. Guys that are smart and have feel and have a good touch, they make the adjustment.”

Concerns, issues, question marks … they are all part of the package that comes with Sullinger. But then you look back at his consistent production and at 21 those questions begin to look like something else. They begin to look like a steal.

“I liked Jared for longer than his years at Ohio State,” Ainge said. “He was a terrific high school player, a dominant high school player. He’s been good everywhere he’s been and his teams win. What I like about him is he’s complete. He can pass. He can think. He can rebound. He can shoot.”

“We think if Jared were completely healthy, if there were no issues, he would be a top 10 pick,” assistant GM Ryan McDonough said. “Jared’s been one of the best players in his class his entire life.”

In addition to Sullinger, the Celtics also took Fab Melo, a 7-footer from Syracuse who went from a curious enigma as a freshman to the Big East’s Defensive Player of the Year as a sophomore. The Brazilian native didn’t begin playing competitive basketball until his freshman year in high school, but he can already do two things that will help him in the NBA: He can block shots and he can take charges.

As Ainge noted, “That’s unique for big guys.” As for his offense, Melo can block shots and take charges, but his rapid improvement at Syracuse offers hope that in time he’ll add more to his game than lobs and put-backs.

In the second round, the Celtics tapped the Syracuse program again for Kris Joseph, a 6-foot-7 forward who can shoot and score in transition. On a deep team, Joseph was actually the team’s leading scorer, but he’s 23 years old and didn’t always put up consistent numbers.

Maybe Melo can contribute right away as a backup center. If nothing else he’s protection for Greg Stiemsma, who’s a restricted free agent. Maybe Joseph can carve out a niche and the Celtics could definitely use some young legs on the wing.

But really, this draft will be defined by Sullinger. If his back holds up, the Celtics grabbed a lottery talent in the latter third of the first round. He immediately becomes the second-best post option after Kevin Garnett -- assuming Garnett signs on for another tour of duty. He’s a huge upgrade on the boards where the Celtics have struggled mightily over the last few years. He’s a presence on the block they haven’t had since Leon Powe left and a better all-around talent.

Ainge explored moving up, but in a draft that was long on hype, the rumors turned out to be little more than smoke and mirrors. “We never got to a point where teams wanted to move for what we were offering,” Ainge said. “I’m not sure how close we were. We weren’t going to sell the farm to move up in the draft.”

He let the draft come to him and took a player he never thought he’d have a chance to draft. It’s a gamble, of course, but it’s a gamble worth taking.