BOSTON (CBS) – Celtics head coach Brad Stevens phoned in to 98.5 The Sports Hub’s Gresh & Zolak program Friday afternoon for his weekly interview.

In the 18 months since Brad Stevens took over as head coach, the Celtics have undergone a roster makeover like no other.

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“Somebody said this and I’m not sure if it’s exactly true, but I think I’ve now coached 15 guys that aren’t here anymore in just the short amount of time I’ve been here,” Stevens told Gresh & Zo.

There’s some players you’d obviously like to keep, but part of that turnover is bound out of necessity, as Stevens noted.

“We were in a roster situation where there was bound to be a lot of change. Part of the bigger moves that were made over the last couple years created some contract things that we had to take on, and that we have to do the very best with who’s here.”

In the last few weeks, team president of basketball operations Danny Ainge has lived up to his “Trader Danny” moniker. In fact, after the latest trade that sent Austin Rivers to the Clippers, Ainge has made an astounding nine trades since July.

That’s a tough situation for any coach to deal with, let alone a man in his second year in the NBA.

Even still, Stevens expectations are the same.

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“We’ve become a really young team over the last couple of weeks, more so than when we started the season and we were still relatively young, playing a lot of young guys,” Stevens told Gresh & Zo. “Rajon Rondo was 28, Jeff Green was 28 and that’s still pretty young, but now even more so. The key is to focus on building good habits. That’s always been the case, but we’ve really got to hone in on that with these guys. Our team has to continue to focus on the things that it takes to be successful, starting with our preparation — both individually and collectively — to play each game.”

98.5 The Sports Hub is the radio home of the Boston Celtics, and you can hear Sean Grande and Cedric Maxwell on the call starting 30 minutes prior to every tip-off.

But occasionally Grande and Max aren’t always able to fulfill their obligations, and fill-in broadcasters are required. Sports Hub’s own Jon Wallach has even gotten the call to replace Grande.

“What was it like having Wallach on the team flight [the other night]?” a sarcastic Scott Zolak asked Stevens. “He’s the kid with the big eyebrows. He did the [Raptors] game [last Saturday]. He’s one of our morning guys…”

“My biggest problem with it is I think we’re 0-2 with him. That’s my only thing. Otherwise the questions were great, we liked having him around,” said Stevens. “I think we’re gonna give him another shot.”

Listen below for the full interview to hear Stevens’ take on the Jeff Green trade, the AFC Championship game and more:

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Hear every game of the 2014-15 Boston Celtics season on 98.5 The Sports Hub — the flagship station of the Boston Celtics. Pregame coverage with Sean Grande and Cedric Maxwell begins 30 minutes prior to every game! Occasionally a scheduling conflict will arise, in which case the Celtics can be heard on our sister station 100.7 WZLX.