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Here’s how the Celtics decode opponents’ play-calling

Avery Bradley, the Celtics’ defensive leader, keeps a close watch on what opponents are doing — and saying.Maddie Meyer/getty/Getty

During an early-season game in 2013, Celtics assistant coach Micah Shrewsberry was sitting next to point guard Rajon Rondo, who was sidelined with a broken hand. It was Shrewsberry’s first year coaching in the NBA and he was still adjusting to the transition from college. As Rondo studied the opponent’s offense that day, he turned to Shrewsberry.

“He was like, ‘Hey, when I come back, you better know these play calls, because I’m going to ask you and I’m going to expect them,’ ” Shrewsberry recalled. “And I wasn’t real sure if he was kidding or not, so I made it a deal that I should probably know what they’re calling.”


Three seasons later, Shrewsberry is one of the gatekeepers of the Celtics’ powerful defense. He has many responsibilities, including doing exactly what Rondo requested. There are just 24 seconds to shoot, and there is much less time to figure out what is coming, but the Celtics and their coaches do all they can.

“You have to shorten it down to what’s going to happen that will affect you the most,” Shrewsberry said. “I can’t say, ‘Hey, your guy is going to pass it to the wing and he’s going to cut to the basket. He’s going to set a cross screen, cut across and go here.’

“So you just shorten it down. I may say, ‘Hey, Avery, step up.’ So he knows, ‘All right, my guy’s going to get a step-up here eventually.’

“Or you can start yelling at guys, ‘Hey, pull over. Your guy’s not going to be in the play.’ That means you’ve got to get in the lane and help. So just small, short snippets that they can kind of use.”

Shrewsberry watches film of the opponents’ last five games, and any the Celtics played against them that year. He studies plays run out of regular sets and then dives into specific out-of-bounds formations A report is then given to head coach Brad Stevens.


The breakdowns are a source of intelligence for Stevens, but he consumes a considerable amount of film on his own. Most often, he is more focused on alignments than specific play calls.

“Obviously, if a team’s walking it up the floor and calling out an action and they’ve run it a couple times, you have an idea what’s happening,” Stevens said. “That doesn’t mean you’re going to stop it. Maybe there’s a reason they’ve run it a couple of times.”

When the Celtics gather for pregame shootaround, the coaches share bits of the information with the players without dumping so much that it becomes clutter.

“I watch a lot of film,” said point guard Isaiah Thomas. “I try to learn the name of the play that they call. A lot of teams run the same type of stuff, but they tweak it here and there, so when you play against a team in the Eastern Conference you might play four times, you get a little accustomed to what they run.”

Once the game begins, though, preparation can degenerate into chaos. The onus often falls on the players to adjust on the fly. Guards scan the opposing benches and try to intercept communications that might provide even the slightest edge.

Avery Bradley, the team’s defensive leader, tends to look back and forth between the point guard and the head coach, hoping they will reveal part of their plan. Sometimes during a free throw, Bradley will ask Thomas to stand in the lane for him so he can pull back and direct his teammates on defense.


“Being in the NBA six years, a lot of the calls are similar,” Bradley said. “Like, you know, a flex action, they have certain names for flexes all through the NBA. You can tell.”

Video: Avery Bradley steal vs. Pelicans

Marcus Smart focuses on an opposing guard until the player looks to the bench for guidance. At that point, he will listen to the language used by the opposing coaches. If Smart knows the play, he tells his teammates how to react. If he doesn’t, he stores the information for later or shouts to Shrewsberry.

Arenas can get quite loud, but that makes it difficult for opponents to hear instructions, too. So sometimes an opposing coach will direct plays with simple hand gestures. Those can offer clues as well.

“It happens so quickly,” Smart said. “Most of the time, it’ll be so loud that we’re at the other end of the court trying to yell to Micah and the coaches the play that’s called, and they’re trying to yell instructions back to us.

“It’s kind of hard to hear, plus staying focused in the game and not trying to look over without getting beat or anything, so it does happen fast.”

Video: Marcus Smart steal vs. Pelicans

Thomas said teams tweak their plays and terminology during games, but there is not much variation.


“If you watch enough film, you know teams mostly just run the same plays, other than San Antonio,” Thomas said. “They’ve got counters for almost everything you try to stop.”

When the Celtics sniff out what is coming, it can be satisfying. Unfortunately, even perfect predictions do not always result in perfect results.

“It’s like, ‘Hey, thanks, we knew what was coming, but they have a really good player and they still scored on it,’ ” Shrewsberry said.

Which opponents are the most savvy?

The Celtics say it is obvious when opponents have truly studied plays and actions. Here are their thoughts about some who stand out.

Chris Paul

“When I first got in the league, when I’m playing Chris Paul for the first time, I’m calling my play out and he’s telling his players where we’re going, and I’m like ‘Man, guys have to do that in the league?’” Isaiah Thomas said. “And you follow those types of players and see the hard work they put in to know other teams’ plays, and you know you’ve got to do the same thing.”

Rajon Rondo

Rajon Rondo (right) taught Avery Bradley a thing or two when they were teammates in Boston.AP

“When I was younger, Rondo used to be like, ‘That’s this, that’s that,’” Avery Bradley said. “At shootaround he was basically walking us through the plays. and it’s because he was always paying attention.”

LeBron James

LeBron James and the Cavaliers swept the Celtics in the first round of the playoffs last season.Getty Images

“LeBron is unbelievable. And he’ll know,” assistant coach Micah Shrewsberry said. “I just remember like vividly in the playoffs we ran a play against Toronto at the end of the season last year to win the game and then we lined up in that alignment against Cleveland in the playoffs, and LeBron is like switching guys around and calling out the alignment, what he saw, what he thought was gonna happen. DeAndre Jordan, surprisingly, is really good at it. He’s a great communicator on the defensive end, so if he hears a play call he’s constantly talking.”


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Adam Himmelsbach can be reached at adam.himmelsbach@globe.com. Follow him on Twitter @adamhimmelsbach