In Boston, unless you're the Red Sox, if you aren't a contender, you don't really matter.
The Celtics don't matter any more.* But I don't think they've really mattered since the end of the 2011 season when LeBron finally beat them. They had a short revival during the Eastern Conference Finals last year, but I think the general feeling even then was that it was sort of a second wind for a team that was supposed to be done already.
This year was supposed to be a bit of a victory lap with an outside chance of competing deep into the playoffs again, but once Rondo was lost for the season, the Celtics became just a "moral victory" type of team -- anytime they pick up a good win, it's a nice story, and that's all.
*This all is from the perspective of the general Boston sports media / sports fans. Obviously anybody who bothers to post on this site feels otherwise.