Confidence the key to upswing in play

Jim Davis/Globe Staff

Dwyane Wade (left) had quite a compliment for Avery Bradley, who knocked the Miami star backward with this block Sunday.

Avery Bradley has perhaps offered the Celtics’ faithful hope for a long postseason run by transforming into a consistent asset in a matter of weeks.

His season began slowly, just as it did in his rookie year. Bradley failed to score in the first four games and looked unsure of himself in relieving Rajon Rondo.

Confidence has been the key to Bradley’s ascension. His scoring average has increased every month, as has his role in victories. In Sunday’s 91-72 win over the Miami Heat, he limited superstar Dwyane Wade to 15 points on 6-for-17 shooting, including a game-defining stuff in front of the rim.

The impact of the block knocked Wade on his back, and he told Bradley that his athleticism reminded Wade of himself. That’s quite a compliment, and a sign that the league is noticing Bradley’s defensive prowess.

“Avery’s just a tremendous defender,’’ Paul Pierce said. “Just having him on D-Wade, we knew he could guard pretty much a lot of these [shooting] guards in the league and the [point] guards. I think [Sunday] really gives him confidence to know he can guard the best. He should be on the all-defensive team if he continues to go like this. Not a lot of people know about him but I think everybody was able to see what he’s capable of.’’

The Celtics are a better defensive team with Bradley on the floor, especially teaming with Rondo in the backcourt. What has pleasantly surprised the Celtics’ brass and his teammates is Bradley’s scoring ability. He is consistently knocking down the mid-range jump shot.

That wasn’t always the case. Bradley was a reluctant shooter and launching a jumper was similar to buying a lottery ticket: He hoped for the best.

“I heard questions from all of you - Avery can’t make a shot,’’ coach Doc Rivers said. “I kept saying, ‘He can shoot the ball.’ You know, it’s funny how things happen. He started making shots because he was making layups first. And then he saw the ball actually go in the basket, even though they were layups, and now he’s making jump shots. But it’s amazing what the mind does. So I thought that just happened but it worked out well for him. And Keyon [Dooling], I just think, we forget how hurt he’s been, how many games he’s missed, with a new team. I just think he’s starting to figure everybody out, which is nice.’’

This is the Bradley the Celtics envisioned when they drafted him 19th overall in 2010 after just one year at the University of Texas. Bradley nearly broke his ankle in a pre-draft workout, and the Celtics were convinced he would not have been available at 19 if he were healthy. Bradley’s injury was unusual. His ankle bent inward, causing a bone to chip off and requiring surgery. The long rehabilitation rendered Bradley’s rookie season useless, save a 20-point outing in the regular-season finale against the Knicks.

The NBA lockout also hampered Bradley’s development because there was no summer league. So Bradley headed to Israel for a brief stint, then reported to Celtics’ training camp in December, the organization still unsure of his ability.

His production has changed minds, and so has his eagerness to learn. Kevin Garnett has offered assistance to younger Celtics over the years, only to be rebuffed and soured by their cockiness. Bradley soaks in all information, forming friendships with Rondo, Dooling, and Marquis Daniels.

They pull him aside during games and offer guidance. Bradley accepts all feedback.

“Not only the coaches, but Keyon and those guys are telling me ‘do your work early and make it hard for [opponents],’ ’’ he said. “They are just telling me to keep going, motivating me and that’s the good thing about being on this team. They want the young guys to do so well, not only the young guys but everybody, giving me tips, telling me what I can do better. I really appreciate that.’’

For the first time in his brief NBA career, Bradley played in front of high school teammate Abdul Gaddy, a point guard at the University of Washington who has played with Bradley since first grade. They played at Bellarmine Prep in Tacoma, Wash., but Bradley transferred to Findlay Prep in Las Vegas to better his chances of signing with a premium Division 1 school.

“I know it was fun for him, this is the first game in the NBA with him ever watching me play,’’ Bradley said. “I know he had fun, especially since we played Miami. We talk every day. We’re like brothers. Definitely, [he helps me], he’ll say something after the game what I could have done and I do the same for him.’’