Over the last five games, the Celtics have held four teams below 90 points per 100 possessions. Included in that list are Utah – who ranks seventh in offensive efficiency – and now Miami, who ranks third. Playing great defense is nothing new for the Celtics, who rank third in defensive efficiency, allowing 99 points per 100 possessions, but this a whole other level.

It’s not a coincidence that their defense has become even more ferocious since Avery Bradley joined the starting lineup. It’s not that Bradley makes the Celtics’ defense go, it’s that he makes it even better. Per BasketballValue, the Celtics allow just 96 points per 100 possessions when Bradley is on the court and are five points tougher when he’s on the court than when he’s off. That’s the biggest individual impact on the team.

"He’s the best perimeter defender in the league," Keyon Dooling said. "I bet you if you did a poll around the league and you asked all the guards who they hate playing against the most, it wouldn’t be the guy who scores 25 a night on you. It would be the guy that gets up in your space and takes everything away from you. I really want to echo that message. Avery is the best perimeter defender in the league."

Most of the league already knew that Bradley was murder on opposing point guards. What they are finding out now is that the second-year guard can hold his ground against two-guards, as well.

Take his defense on Dwyane Wade on Sunday in the Celtics’ 91-72 victory. Bradley let it be known early that he wasn’t going to allow Wade to back him down and get interior position without a fight and in the first eight minutes of the game, Wade attempted just one shot.

"I told Avery, just like those guys are special offensively, you are special defensively," Dooling said. "Now go out and just play your game. Don’t worry about the name on the back of the jersey, just go out and play Avery Bradley defense. The kid has no fear. He’s tough. He knows the angles. He’s just an exceptional defender."

The highlight play came when Wade attempted to throw down an emphatic jam and Bradley cold-blocked him at the rim, but away from the ball, Bradley made sure to do his work early. Wade shot just 6-for-17 and was never really a factor. 

"Avery is just a tremendous defender,” Paul Pierce said. “Just having him on D-Wade, we knew he could guard pretty much any of these two-guards in the league, and the one-guard. I think tonight really gives him confidence that he can guard the best out there. He should be on the All-Defense team if he continues to go like this. Not a lot of people know about him but I think today everybody was able to see what he's capable of."

So here’s the intriguing hypothetical, and yes, this is somewhat crazy and probably an uncomfortable notion in some corners of the locker room: Should the Celtics consider leaving Bradley in the starting lineup when Ray Allen returns from his ankle injury?

"I don’t know yet," coach Doc Rivers said. "We’re playing well, but we’ve also played well with Ray, by the way. I think people forget that part. The good thing is we have options. And we have players with confidence and we have a lot of them. That’s where the season has helped. The best part is not Avery for me. Or [Mickael Pietrus]. The best part is Keyon is coming on, so we have an extra guy, and we need it."

There are pros and cons on both sides of the issue for Rivers.

Coming into Sunday’s game, the starting lineup with Bradley at the off guard position is a rather incredible 24 points better per 100 possessions than the opponent. It’s not just defensively. In 151 possessions, they have scored 173 points.

It’s not all Bradley, of course, but a significant addition to the Celtics’ offensive gameplan has been Bradley’s ability to cut to the basket and create easy scoring chances. "I always cut to score, but I don’t always cut just for me," Bradley said. "I cut for my teammates too."

This all comes back to spacing and Bradley’s movement is similar to the effect that Allen’s constant running around picks has on the halfcourt offense. In the past, Allen was often placed in lineups with the reserves and those lineups performed well from a plus/minus standpoint. The Allen effect has been muted at times this season for all sorts of reasons, but it’s worth considering how much better their offense has worked with Bradley, and whether Allen’s shooting ability could provide a lift for a second unit that has struggled to score.

On the flipside, it remains to be seen if Allen’s effectiveness would be limited if he’s not playing with Rajon Rondo, Kevin Garnett and Pierce. Of course, there’s also the important dynamic of what that move could mean in the locker room for a team that is clearly going through transition. We’re not talking about a journeyman here. We’re talking about Ray Allen, future Hall of Famer and a player who has earned his place in the team’s hierarchy.

Regardless, Rivers said that he will try to find a way to get Bradley and Rondo on the court when Allen does come back.

"No doubt," the coach said. "[Bradley] and Pietrus. They’re such tough defenders and they give you a disposition. We’ve already got Kevin on the floor and I think with Avery and Pietrus they give Rondo life defensively. He feels like, I’ve got some guys out here that can put pressure on the ball."

What Bradley also does is make the Celtics more versatile defensively.

"I think Avery can guard ones and twos," Rivers said. "He struggles a little with three’s. We have three guys that can do that. Pietrus can guard one-two-three. Avery and Rondo can guard one and two and he’s guarded three’s at times. That’s something we have not had. We’re switching things that we would never switch. It’s allowed Kevin and Brandon [Bass] to stay closer to the basket, which has helped us."

Ultimately, this is an incredibly positive development for the Celtics. Bradley came into the season with no set position and no role. He’s emerged as an elite defender and an intriguing offensive player who seems to get better by the game. Not only is he a valuable part of the future, he’s also becoming an integral part of the present, no matter how Rivers chooses to set his lineups.