Most of the Boston Celtics players were on the floor at Miami's AmericanAirlines Arena for a morning shootaround before last week's matchup with the Miami Heat when Ray Allen spotted a pack of reporters encircling a player on the opposite sideline late in the media session.

Allen looked around at the personnel on the floor, offered a confused look, and asked a teammate who could possibly be in the crowd. Both turned and craned their necks to see who was sitting in front of all the microphones. Their reactions said it all.

Greg Stiemsma has given the smallish Celtics a much-needed shot-blocking presence. Jim O'Connor/US Presswire

"Stiemsma?!"

As if the veterans needed another reason to get on the case of rookie center Greg Stiemsma. Nursing a bone bruise in his right foot -- the most serious of a smorgasbord of maladies that includes a case of plantar fasciitis in his left foot, a jammed right thumb and a right pinkie finger that lost a small chunk when he blocked a shot and hit the backboard -- Stiemsma hadn't participated in a shootaround in about a month.

Naturally, the veterans have given him plenty of grief about his lack of participation.

"A little bit, especially being a rookie," Stiemsma said with his familiar smile. "It's kind of a veteran excuse, to just play in the games."

A lack of big men on the Celtics' roster has opened the door for Stiemsma in his first NBA campaign, and he's not going to let injuries prevent him from taking advantage. Even though he hobbled off most nights in March wearing a cumbersome black walking boot on his right foot, it allowed him to grind through the game-heavy schedule and establish himself as a key rotation player on the Boston bench.

More impressively, Stiemsma just keeps improving. Even without practices or being able to take part in shootarounds, he's been able to develop his game -- particularly on the defensive end, where he was a bit of a liability early in the season.

Now his rotations are crisper, his pick-and-roll play is improving, and he's using his shot-blocking talents to become an impact player on that end of the court.

On Sunday night in Charlotte, with newly minted Eastern Conference Player of the Week Kevin Garnett getting a day of rest at the tail end of a back-to-back-to-back, Stiemsma jumped into the starting lineup and responded by filling up his stat line to the tune of 8 points (on 4-of-4 shooting), 6 blocked shots (matching his career high), 5 rebounds, 4 steals (also matching a career high), and an assist over 27:57.

On his first shift Sunday, Stiemsma blocked three shots and threw down an alley-oop. He even managed to avoid those pesky whistles in the first half, only to be tagged with four fouls in a span of 3:37 in the third quarter to take some of the momentum out of his night.

Even that did little to temper his coach's praise.

"Greg, defensively, he's a force," said Celtics coach Doc Rivers. "He's a great shot-blocker. I don't think the officials know that yet."

Rivers thought Stiemsma got some bad whistles and that block number could have been even higher. Stiemsma is 15th in the league with 1.56 blocks per game, but his 5.38 blocks per 48 minutes is second only to Oklahoma City Thunder shot-block king Serge Ibaka (3.63 per game, 6.44 per 48 minutes).