Amid injuries, Ronnie Brewer began the season as a starter and played a nice role in the Knicks’ 18-5 start. But soon he lost confidence in his 3-point shot and slid from starter to 15th man.

Thursday Brewer got his wish as he was dealt at the trading deadline. The Knicks sent him to Oklahoma City for a 2014 second-round pick.

According to a source, Brewer’s agent, Henry Thomas of CAA, asked the Knicks to see if there was interest from another team. It worked out because the Knicks were needing a roster spot to sign a big man and used it yesterday for Kenyon Martin.

The Knicks also got a small trade exception in the deal they can use this summer when they will be desperate. The Knicks, under a new collective bargaining agreement rule, won’t be able to do any sign-and-trades for free agents.

“Ronnie had fallen out of the playing rotation, he was a great guy, good player, but an opportunity came up where a very good situation with a team very interested,’’ general manager Glen Grunwald said. “We wanted to help him out best we could and give roster flexibility for our team.’’

Brewer hadn’t been in the rotation since early January, but early on made a good three-guard combo with Raymond Felton and Jason Kidd. Brewer made 34 starts before falling out of favor and becoming completely extraneous when Iman Shumpert returned in mid-January.

Brewer, who played last season for Chicago and signed with the Knicks for the one-year minimum of $1.3 million, is shooting 36.6 percent from the field and 31.1 percent from 3-point land.

Brewer may have been bothered by his knee, on which he had surgery in September, but refused to ever use it as an excuse.

Woodson said Thursday at practice he may change the starting lineup to infuse some offense. Rookie Chris Copeland is a candidate to come in for offensively challenged Jason Kidd or Shumpert.

Woodson said he has been disappointed in the lack of offensive production from starters Shumpert and Kidd, who was scoreless Wednesday.