For a team that doesn't have any cap space, spending the max or something close to it for Smith is really of no concern.
If a team has cap space, spending it on Smith would be a mistake, unless you already have a core of 3 or 4 talented players already signed, and Smith is simply the missing piece of the puzzle.
As it is, I don't see the Celtics playing the cap game any time soon. Though there'll be a lot of cap room within a couple of years, but at the expense of not having anyone under contract, so that's kinda of a faux cap space I really want no part of and really of little use.