Coming here he wouldn't have to be "the man" he was this year in ATL. Less hero ball increased shot %. Even though doc is gone, rondo can teach him something about his shot and definitely get him the shots he needs and can make not the ones he just feels like taking. Only thorn is that ft%, can't fix that 
That FT% issue is actually quite important. Putting all of Smith's other flaws aside, we have to keep in mind that if we do bring in Smith with Rondo, that gives us two key players who also happen to be free throw liabilities in late game situations.
The reality is they aren't really liabilities in late game situations.
You're telling me you wouldn't worry at all when Rajon Rondo or Josh Smith take critical free throws with the game on the line?
Rondo and Smith both normally hit over 60% of their free throws. That works out to more than 1.2 point as per possession, which is higher than the scoring efficiency of any team in the league in most seasons. People have been fretting over hack-a-Rondo for years, yet we've never really seen it. That's because of simple math. Teams are better off letting the Celts try and score than fouling Rondo.
It's true that a team that's behind late in the game that has to intentionally foul will go after one of them but that's a fairly manageable issue.