Based on how the Boston Celtics’ roster is currently assembled, they need to be greater than the sum of their parts in order to succeed. 
The Celtics undeniably lack star power right now. According to ESPN’s preseason rankings of the league’s top 400 players, Isaiah Thomas is Boston’s best player at 65th overall. Only the Nuggets, Lakers and Sixers have their top player ranked lower. Yet through 13 games, Boston boasts a statistically elite defense thanks to coach Brad Stevens and a roster that has bought in and exemplified all the tools you need to defend at a high level.
Boston ranks in the top 10 in eight different defensive categories, from defensive rating and steals to forcing turnovers and opponent field goal percentage.
| Celtics Defense | No, | NBA Rank |
| Turnover Pct. | 17.1 | 1 |
| Steals | 11.5 | 1 |
| Turnovers | 19.2 | 2 |
| D Rating | 99.1 | 4 |
| FG Per Game | 35.2 | 4 |
| Effective FG % | 47.7 | 6 |
| FG % | 43.2 | 7 |
| Points Allowed | 97.8 | 9 |
Boston has seven players who log at least 20 minutes per game, and five of them have defensive ratings below 100 points allowed per 100 possessions while on the floor.
“You’re not going to have a good defense without guys that are willing to play it and without guys that are physically able to do it,” Stevens said. “And those guys really enjoy it. They enjoy guarding somebody. They enjoy the challenge that comes with it and they take pride in it.”
That cannot be said for every NBA player. But the Celtics have a bunch of them, and they spoke about the team’s defense with SheridanHoops. They emphasized quickness, communication, intensity, togetherness, ball pressure and scouting— among other things— that make their defense tick, despite not having a marquee name, so to speak.
For Boston, defense starts on the perimeter with guards who hound opponents just after they get past mid-court.
“I think we have two of the best on-ball defenders in Marcus Smart and Avery Bradley,” veteran forward David Lee told SheridanHoops, “and I think that they heat the ball up. And when it takes longer to get in your offense and when the guards have to start the offense higher up because of the ball pressure, I think that sets up our defense.”
Ball pressure, or heating the ball up, does a few things to make life difficult for opposing offenses. It takes time off the shot clock, forcing teams to rush things and make an errant pass or take a quick shot. The offense also has to start further from the basket, which takes teams out of their comfort zones.
Despite Boston being fifth in pace, it allows the fourth-fewest field goals per game with 35.2. That starts with the backcourt of Bradley and Smart, who is out at least two weeks with a lower leg injury.
In Smart’s first game out, Boston surrendered 111 points to Brooklyn in a loss on Sunday. Isaiah Thomas drew the crunch-time minutes on Nets guard Jarrett Jack, who repeatedly backed down his 5-9 foe.
Boston added Thomas and forwards Jae Crowder and Amir Johnson over the last nine months, which Stevens said improved the team’s quickness and versatility defensively.
“You add Amir at the 4, who’s long, quick, agile, can guard a bunch of people,” Stevens said, “and the guards continue to get more comfortable together.”
And as the team has grown more comfortable together, it has been able to pick up its intensity from last season.
“I think that was our focus going into training camp was picking up the defensive intensity,” swingman Evan Turner told SheridanHoops. “We try to deliver the first blow and compete. We come out and we try to pick up the intensity and communicate. I think the biggest thing we worked on is communication.”
“Miscommunication is the biggest factor when a defense screws up,” forward-center Kelly Olynyk said.
When a team plays together, communicates and plays more intensely on defense, good things happen. A credit to Stevens and his staff is how Boston scouts its opponents. Turner and Lee both emphasized how much it helps them going into games.
“I think one thing that we work on and do a good job of is scouting,” Lee said. “We just have certain things we want to take away from the other team and we have their main plays down.”
All the different elements just mentioned— ball pressure, intensity, communication, quickness and scouting— have led other teams to turn the ball over more than the Celtics had anticipated. As shown in the chart above, Boston leads the league in steals and turnover percentage and is second in turnovers forced per game, according to Basketball-Reference.
“I think the biggest thing that’s been a surprise for me is that we are turning people over,” Stevens said. “We don’t talk about it, but our guys are in pretty good position and aren’t taking plays off, and as a result are coming up with some steals and it’s helping our offense.”
Bradley said that you can try to not be solid on defense and gamble for easy steals, but that’s not what the team is doing. Bradley is among four Celtics who average at least 1.5 steals per game, led by Crowder, who’s second in the league with 2.6 thefts and first in steal percentage.
Crowder is one of the league’s most underrated defenders at 10th in the league in defensive rating, just behind teammate Jared Sullinger.
“Turning people over isn’t a huge deal for us,” Olynyk said. “It’s more about being solid and limiting people to one shot and one tough shot.”
Turner said that forcing turnovers and getting steals are just a natural by-product of strong defense.
“If you get a bunch of assists, odds are you’re making shots,” Turner said. “It comes with it. We’re just trying to benefit from our energy and our preparation.”
But without Smart, the team’s perimeter defensive anchor, they will have to rely more heavily on Bradley, Thomas and Turner.
“How well our depth plays is going to determine how far this team goes,” Lee said. “And when you can have fresh bodies on the floor and play with consistent energy over 48 minutes, that’s a lot easier than when you’re playing five guys the whole game and guys get tired defensively and take possessions off.”
Despite Boston’s stats, the Celtics aren’t being talked about that much in NBA circles in the early going. Stevens doesn’t like talking about the team’s defensive prowess because it is something the team has to keep doing each day.
“You have to prove it and re-prove it every day and we have played thus far with multiple efforts,” Stevens said.
“I think you’ve got to earn your respect,” Turner said. “The league is like a circus sometimes, you’ve got to have an attraction in order to get attention. We’ve got a group of guys that gets the job done and I’ll leave it at that.”
Shlomo Sprung is a national columnist for SheridanHoops who focuses on analytics, profiles and features. He is also the web editor of the Brooklyn Daily Eagle. A 2011 graduate of Columbia University’s Journalism School, he has previously worked for the New York Knicks, The Sporting News, Business Insider and other publications. You should follow him on Twitter.