Sometimes an unscheduled gathering of senior staffers can develop a rhythm and go long into the night. Ainge might see footage of one guard and then want to compare clips of similar players. Then the group might realize it has neglected centers, so they switch to watching them.

Amid all the visits, phone calls, and workouts that are part of the Celtics’ draft preparations, some of the most valuable information is gleaned from intimate and animated staff meetings in the second-floor office of president of basketball operations Danny Ainge.


“Then somebody calls you, and you’ve been watching for four hours, and someone calls with a potential trade offer and then you watch some current NBA guys,” Zarren said. “And then the trade offer includes a pick in a different area of the draft, so you say, ‘OK let’s watch these guys, too.’ ”

Then an impromptu session has turned into something more, and then it’s time for a burrito run. Ainge prefers to watch clips as a group, because one person might notice something the others do not. It could be a flaw in a player’s shooting mechanics, or simply how he interacts with teammates.

“Watching together is good,” Ainge said, “because it breeds conversation.”

Even after the Celtics’ decision-makers go home late at night, it is common for the dialogue to quickly reignite on a group text-message string. Sometimes it just can’t wait until daybreak.

“It’s hard to turn your brain off, even when all of us leave at 10 p.m.,” said director of player personnel Austin Ainge. “And then the next morning we’re back there with all these ideas.”

This spring, the process has new urgency for the Celtics. They are in position to ascend from good to great more quickly than most imagined, and they will be an overwhelming presence at Thursday’s NBA Draft, with eight of the 60 total picks, including the third overall choice.


Ultimately, final decisions are made by Danny Ainge. Often, he will not even tell his staff which players he is leaning toward, because he does not want to cloud their evaluations. But Ainge is hardly alone as he untangles these conundrums.

Strength is not in numbers

The Celtics have one of the league’s smallest and most airtight collections of executives and evaluators.

The five key figures are Zarren, Danny Ainge, Austin Ainge, director of scouting Dave Lewin, and coach Brad Stevens. There also is a handful of scouts and a few analytics experts, and that, essentially, is it.

“The more people you have, the more people you’ve got to manage,” Danny Ainge said. “Manage schedules and personalities, and manage who’s fighting for air in the room in our meetings. And so we feel like we have the right amount of guys that cover all the territories, and if we ever felt we need more, we’d bring in more. I’ve got a couple hundred résumés.”

Ainge trusts this group and encourages animated discussion and debate, particularly when it veers from his thinking.

“Danny likes arguing,” Zarren said. “That’s the other thing about this group, is that it wouldn’t work if one of us was shy. It just wouldn’t. And when you have a really small group, there can’t be any weak links.”


Director of player personnel Austin Ainge (left) and coach Brad Stevens. Associated Press/File

The main roles seem clear. Zarren, the assistant general manager, leads the analytics staff and is the salary-cap guru. Austin Ainge heads the scouting department, with an emphasis on overseas players. Stevens’s knowledge of the rest of the NBA — players the Celtics might want to trade for or sign — is essential.

But no one is pigeonholed. Having a small staff makes it more important to be versatile. Analytics experts Drew Cannon and David Sparks, for example, go to NCAA conference tournaments to help scout.

Zarren, a Harvard Law School graduate and former management consultant for Fortune 500 companies, did not have a deep background as a talent scout when he arrived here. But when Chris Wallace left Boston to be the Grizzlies’ general manager in 2007-08, Zarren began to take on more responsibility, and he now holds a considerable role as an evaluator.

Some general managers are focused primarily on personnel matters, like trades and signings, while delegating some of the most exhaustive college scouting duties to staff members. But Danny Ainge is known as a voracious consumer of film.

“I’ll put Danny’s video-watching up against any NBA general manager in terms of sheer volume,” Zarren said. “He’s great because he grinds.”

Stevens dives deep

While many on the staff are scouting college prospects during the season, Stevens is focused on his team. But his deep knowledge of the rest of the NBA is helpful during the offseason, when Boston is identifying free agent or trade targets.


During the summer, Stevens assigns a group of NBA players whose games he admires to members of his coaching staff, and they compile full reports on what makes them tick.

“Brad certainly dives deep into certain guys around the league, and his perception of those guys is really valuable,” Zarren said. “You’re evaluating, ‘Do I like who we’re likely to get at Pick X more than this set of NBA players we could get in a trade involving Pick X?’”

Stevens is just three years removed from college coaching, so he is still familiar with many of those players. Ainge gave him a list of eight prospects to study for the No. 3 overall pick, and there are seven picks after that to prepare for, too.

Stevens likes actual game footage, specifically the endings, when players reveal how they handle high-tension, high-stakes moments.

“We’re constantly talking about these players for years,” Austin Ainge said. “We have arguments about them, and then Brad comes in pretty fresh. He’s seen some of the guys, but he’ll come in fresh and will say, ‘Hey, I watched a couple of hours of film on this guy. This is what I’m seeing. How come we don’t have him higher or lower?’ ”

Often, Stevens mentions something no one had considered, and then they go back to the tape, and then it might be time to settle in for a late night.

Workouts a piece of the puzzle

Over the past two months, the Celtics have overseen about 180 individual workouts — many of them duplicated — either at their training facility or at sites around the country arranged by the players’ agents.


The workouts have value, and because they occur so close to the draft, there is a tendency to place added importance on them. But the Celtics view the process through a larger prism.

“I think that’s the dangerous part — the last days of an evaluation as opposed to what they’ve done for a year, or in three or four years of work,” Danny Ainge said. “And I guess that’s my job, to determine that.”

Even setting up a workout can be a complicated, secretive task. If an agent believes his player should be selected before a team is scheduled to pick, he will often decline the workout invite. The elite prospects, meanwhile, rarely work out against other players. The thought is that if they dominate an inferior player, it was expected; if they struggle, their weaknesses could be revealed.

When the Celtics won the 2008 NBA title, the long season forced them to get creative because time before the draft was short; they even flew prospects to Los Angeles for workouts while the team was there to face the Lakers in the Finals. This year, given Boston’s bounty of picks, it has been a preferred destination.

At the workouts — the only time during this process when Austin Ainge turns off his cellphone — they are testing athleticism and conditioning. But it is also a time to gauge perceived weaknesses, from a poor off-hand to a question about a player’s past.

“Most of the time it doesn’t matter if it’s the No. 1 pick or No. 60,” Austin Ainge said. “Every guy has a thing or two you’re worried about, or four things you’re worried about, and some things you really like.”

The Celtics bring in some players for second workouts closer to the draft. California’s Jaylen Brown was back here Monday. Fans tend to view these return trips as indicators of great interest, and sometimes that is true. But other times, the purpose is to poke around about a concern.

“There have been callbacks where the guy was banged up or tired and so we said, ‘All right, let’s look at you again,’ ” Austin Ainge said. “Or sometimes we found some things out in their background check, and we want to talk to them about it.”

Prepared for anything

Months and even years of preparation will reach a temporary end when the brass gathers in its war room for Thursday’s draft. It is impossible for the Celtics to know exactly what they will do, because so much depends on the decisions of other teams.

Amid all the uncertainty, one certainty is they will be prepared for anything. They will have combed through the rosters of the 29 other teams and noted players they have interest in, and they will have identified certain trades that they would make to acquire them.

In the draft room, the Celtics will have crib sheets that list every team’s current contracts, salary-cap situations, and collections of current and future draft picks. They also will have detailed reports on hundreds of prospects, including medical histories that can be important if a highly rated player makes a surprising fall.

“And, you know, like, what if the power goes out?” Zarren said. “That room has to be prepared no matter what happens. They don’t stop the draft for you. They don’t stop it if you get three trade calls and you have just four minutes on the clock and have to evaluate those possibilities quickly.”

The Celtics even have an established chain of command if multiple trade calls come in at once. There are just five minutes between picks in the first round and two minutes in the second round, so once the draft begins, it is important to keep up.

During this hullabaloo, there also will be calls from agents looking to find out if the Celtics plan to draft their clients. It might seem best to ignore those inquiries at such a chaotic time, but agents often have information about other teams, so their calls have value, too.

“In the position we’re in this year,” Zarren said, “there’s so many different possibilities that if you’re not excited to be working here, something’s wrong with you.”

There have been years when Danny Ainge essentially finalized his list of draft candidates a week before the draft, and there have been years when the draft was just three hours from commencing and he still did not have final preferred choices.

“You hear the phrase a lot that you’re going to take the best player available, but certain points in the draft, it’s not so obvious and gets a little cloudy and murky,” Ainge said. “So, often times, you do select someone that fits your team’s personality or fits your team’s needs.”

The Celtics will ultimately be judged by the success of the players they select, but that snapshot wouldn’t be an accurate gauge of the team’s full evaluation process.

So Austin Ainge, for example, will eventually go back and see how his top 100 players fared, no matter if they were the No. 1 overall pick or D-League grinders. He will see where he missed and try to figure out why, and then the entire process will continue, and the late nights will keep rolling.

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