That's the $1 million question. Or at least the prorated veteran's minimum of $1.1 million question. And neither Finley nor Celtics coach Doc Rivers professed to know the answer Sunday, but both expressed optimism about Boston's recent addition of the veteran swingman.
"I don't know [my role], that's the big question," admitted Finley, who joined his teammates for the first time at Sunday's tilt with the Washington Wizards.
Finley asked for and received a buyout from the San Antonio Spurs last week.
"I just think that I will not hurt anything that [the Celtics] have. This was already a great team without me. I come in, maybe [provide] a little veteran expertise, whether that be on the court or in the locker room -- just doing whatever I can to make this team a better one. But, like I said, this was already a great team before I got here, so I think that my addition is not going to be that big of an impact, if any, but I am just happy and excited to be here.
"Coach [Rivers] was pretty honest with me, which I respect. He doesn't know how he's going to use me. I have to respect that. I'm coming to a situation where, the team is already established. They've put in  games of time, so for me to try to establish a role would be crazy to think like that. But coach has put me in a situation at ease, where he doesn't know, I don't know -- when my situation comes, I'll just go out there and play hard and do what I can to help the team be a better one. I think that I am able to do that."
Finley arrived in Boston late Saturday night, underwent a physical, and finalized a free-agent contract to cap his 37th birthday celebration. After a session with Boston's assistant coaches Sunday morning, Finley went through about a half-hour warm-up on the court at the Garden before the Wizards game, but was inactive.
With 12 healthy bodies, including fellow guard Tony Allen, who missed Friday's game at Philadelphia with a sore right hip, Rivers saw no need to rush Finley into action without first getting him acquainted with the system.
"I don't know [when Finley will play], I really don't," said Rivers. "He may play in the Milwaukee game [Tuesday]. We'll wait and see how comfortable he is, how quickly he can do it. It might be the worst month ever [to join midseason], because there's no practice days, we play just about every day. We're just going to figure this one out on the fly."
Finley admitted he had to be patient. But sitting in a suit at the end of Boston's bench Sunday, you have to figure he was fighting the urge to rush to the locker room for a jersey as the Celtics struggled for three-plus quarters against the lowly Wizards.
"I think the biggest adjustment for me is just trying to come in and be perfect right away," said Finley. "In a situation like this, I want to help so badly. I want to do all the perfect things, I put a lot of pressure on myself and that can be detrimental not only to me, but the team as well. I'm just going to try to ease in, ease my role, and just ultimately play basketball."
Finley brings two key attributes: perimeter shooting and veteran experience. With 1,082 career games, he joins Kevin Garnett (1,104), Rasheed Wallace (1,066), and Ray Allen (1,001), making Boston only the third team in NBA history to boast four players with over 1,000 games experience, according to Elias Sports Bureau.
If Boston is to remain healthy down the stretch, Finley's addition could force Rivers to make a tough decision on who to make inactive. While Boston could surely use a shooter like Finley, it means moving an end-of-the-bench presence like Brian Scalabrine or, more likely, Shelden Williams to inactive with 13 bodies in Boston (Marcus Landry, the team's 14th and final player, is on assignment in Maine).
Finley is not only a veteran of 111 playoff games, but regarded as a top locker room presence. He entered the Celtics' clubhouse Sunday and dropped a towel over the head of Marquis Daniels, who he was teammates with in Dallas, and joked, "You're still a rookie to me."
Ultimately, Finley hopes a role will define itself. But he also admitted that there's not guarantee how this will all play out.
"Unfortunately, for me, I couldn't finish something that I had in San Antonio because the role was something that I really didn't agree with," said Finley. "But here, hopefully the situation will be different, but you never know, it may be the same. But I'm happy with my situation now and I'm definitely going to make the most of it."
Finley may not know his role, but here's a few things he did know and expound upon Sunday:
On choosing No. 40: "Well all the good numbers were taken. I was going to go for 33 [Larry Bird], that was gone, 32 [Kevin McHale] was gone, so I decided on 40. I couldn't get 4, I was two weeks too late to get my No. 4 with Nate Robinson coming over, so I just added an imaginary zero to it and made it 40."
On the injured ankle that limited him to 25 games this season: "I'm still doing rehab, it was a severe ankle injury that happened back in December so my rehab will continue for the remainder of this year and probably throughout the summer but I'm very confident in it. I talked to the training staff here, and they're an excellent one that I'm just learning the past couple of days, with that being said, I'm ready to go."
On what went wrong in San Antonio: "This all happened within a week, a week or two span. It was something that started as something little and I think it just erupted. I think both sides, myself and the Spurs organization, there was a mutual split. I have no hard feelings with them, it was just something they were willing to do, and I was man enough to be ready to make that move."
Chris Forsberg covers the Celtics for ESPNBoston.com.