MILWAUKEE – When Avery Bradley was traded to Detroit and Jae Crowder was included in the Kyrie Irving trade with Cleveland in the offseason, the belief was that the Celtics’ defense wouldn’t be as good this season.
 
Folks were right.
 
It’s not as good … it’s better.
 
At least it has been through the first five games of the season.
 
Boston (3-2) heads into Saturday’s game at Miami riding a three-game winning streak in large part because of a defense that’s off to a fast start.
 
On the surface, the easiest barometer for their success lies in the fact that teams have collectively struggled to score against them this season.
 
Teams are scoring just 96.0 points per game against Boston which is tops in the East, and fourth overall in the NBA.
 
Boston’s 96-89 win at Milwaukee on Thursday night was the Celtics’ second straight game holding an opponent under 90 points scored.
 
“It’s great team defense,” said Boston’s Daniel Theis who made his first NBA start on Thursday. “Two games in a row now, under 90 points, that’s really good defense.”
  
A deeper dive reveals Boston’s strong play defensively is a multi-faceted, multi-layered approach that for the most part, has involved various all working in concert with each other most nights.
 
That’s why there’s no one or two statistical categories that jump out to help explain why Boston’s defense has gotten off to a really strong start.
 
If you hone in on the analytic numbers this season, you’ll see a pattern of the Celtics ranked among the league’s best in just about every meaningful statistical category as it relates to defense.
 
Boston’s defensive rating of 95.9 ranks third in the NBA. And Boston’s defensive rebounding percentage, a key stat to any team’s chances at success as a collective group defensively, is .815 which is the fifth-best mark at this point in the NBA.

Steals (9.0, 7th in the NBA), opponent points off turnovers (13.2, second) and opponent effective field goal percentage (.482, 7th) are just some of the areas in which Boston’s defense has been impressive this season.
 
Here are five more reasons why Boston’s defense has been so good thus far this season:

With all the changes made by Boston in the offseason, one thing that probably doesn’t get enough attention is the fact that the Celtics became a team with significantly greater length at just about every position on the floor. Jayson Tatum and Jaylen Brown in the starting lineup provides a major boost length-wise to the Celtics roster with their ability to switch all the time and not lose much if any ground in terms of having the ability to contest shots because of their long wingspans. And while defense is not necessarily a strength of Kyrie Irving’s game, his length at the point position has been helpful. The 6-foot-3 guard came into Thursday’s game against Milwaukee with a team-leading 13 deflections this season.
 
 

There’s no getting around the fact that Boston’s defense plays with more force than finesse now. A big chunk of that credit should go to Aron Baynes who has been the physical banger this Celtics team desperately needed. In many ways, Baynes’ play has helped set the tone defensively for Boston when he’s on the floor. Throw in Marcus Smart being well, Marcus Smart along with rookie Daniel Theis who has shown no fear in mixing it up inside the paint … you have a team that talks tough and then goes on the court and backs it up.
 
 

How many times have we seen Marcus Smart make a play that just blows up an opponent’s plans offensively? Well, the Celtics have a few players this season who have shown the ability to impact the game that way in spurts. Terry Rozier’s aggressive brand of defense quickly moved him to the top of Boston’s wish list in 2015 when they were picking at No. 16. Daniel Theis was a Defensive Player of the Year award winner in Germany, in part because of his ability to take offenses out of what they wanted to do. And while his minutes have been limited, rookie Semi Ojeleye has shown he too has the potential to be a defensive specialist. The way he guarded Giannis Antetokounmpo down the stretch in Boston’s 96-89 win on Thursday was impressive for any player in this league, let alone a seldom-used second-round pick in his rookie season.
 
 

When he was at Butler, his teams were often among the better ones defensively so it comes as no surprise that the Celtics have been solid at that end of the floor. But now, Stevens has more the kind of talent that allows him to do so many more things defensively that he couldn’t do in the past. And once the shock of losing Gordon Hayward wore off for this team, players have bought into what they need to do in order to be a great defensive team. And a lot of that credit has to go to Stevens who has managed to find different combinations that do a lot of things well, but the foundation for them all lies in their defense. And if that’s your foundation, regardless of who is healthy or not, chances are high that you’ll win a lot of games even on nights when you don’t play your best as a team.
 
 

It’s certainly too soon to talk about Al Horford as a Defensive Player of the Year candidate. But in terms of being an all-NBA defender, a strong case can be made that at a minimum he’s played well enough to be in that conversation. He is often praised for his versatility both as a scorer and defender. But it is Horford’s defense, particularly this past week, that has been impressive. But the one matchup that will stand out for most involves his defense on Milwaukee’s Giannis Antetokounmpo, a legit league MVP candidate who came into Thursday’s game against Boston having scored at least 30 points in each of the Buck’s previous four games. The Greek Freak finished with a double-double of 28 points and 10 rebounds, but don’t let the numbers fool you. He did not dominate this game; Horford’s defense on him did. And to top it off, Horford had 27 points and nine rebounds of his own. When he’s defending like that and getting buckets and boards, the Celtics become of the best teams in the NBA