Celtics bring in Finley

Finley gives the Celtics a proven shooter off the bench and allows them to stretch the floor and give space to Kevin Garnett and Kendrick Perkins in the paint.

Finley was released at his request and the Celtics contacted Thomas this week to show their interest. Finley averaged 3.7 points in an injury-filled season, his fifth with the Spurs.

“The opportunity to earn minutes in the rotation. And the chance to seek a ring and the chance to play for Doc [Rivers] and with [Kevin Garnett] and some of the other guys. All of those things made Boston attractive,’’ Thomas said.

Finley suffered a badly sprained left ankle early in the season and was limited to 25 games. When he re turned, he was out of the rotation and requested to be waived. General manager and coach Gregg Popovich reluctantly agreed.

“It was difficult in the sense that he grew very fond of the organization,’’ Thomas said. “It was an organization where he won his first and only ring. He has nothing but respect for his time there. This was a rather sudden thing for him.’’

Finley has piled up more than 17,000 points since entering the league with Phoenix in 1995 out of Wisconsin. He was picked 21st - long after Rasheed Wallace (No. 4) and Kevin Garnett (No. 5). He played 8 1/2 seasons in Dallas before signing with the Spurs after the Mavericks bought out his contract. He is a career 37.4 percent 3-point shooter, but 31.7 percent this season.

“He is very excited about playing with the guys on the team,’’ Thomas said. “He still thinks he has the ability to contribute some things on the court and provide the things to the team that they need to get another ring.’’

The Celtics are already among the oldest teams in the league and it is uncertain how much Finley has left after 1,082 games. But Ainge is looking to shake up the roster and had two available spots following the three-for-two trade with the New York Knicks that netted the team Nate Robinson.

Players needed to be waived by March 1 in order to be playoff eligible for another club.

“I think the Spurs understood at the time not really being in the mix for the first time in his 15-year career,’’ Thomas said. “They were very understanding of his situation and the fact he felt he still could contribute. [Not playing] was a difficult thing for him to handle.

“Unlike guys his age, normally it’s sort of a gradual thing, they move into the reality of being on teams and not being part of the mix. That wasn’t his experience.’’

Finley has played in 101 career playoff games, averaging 13 points. He averaged 11.2 during the Spurs’ 2006-07 title run, including 41 percent from the 3-point line.

Gary Washburn can be reached at gwashburn@globe.com.