Jefferson is not now nor has he ever been a force on defense. The Spurs offense is humming along fine (forget about last night in Detroit), I can't see the FO messing with this team until season's end; unless it's to trade Blair and maybe Neal before the deadline for future help.
Outside of some of the espn 'experts' who haven't watched the Spurs play, a lot of folks around the country are beginning to notice that the Spurs as currently constructed are one of, if not the best and deepest teams in the west and maybe the league.
Al Jefferson wouldn't be a player who would put them over the top, now Kobe? maybe...
Since you can't fix stupid, at least you should be able to prosecute it!