I think Smart surpasses Tony Allen but it is hard to find a comparable player. What Smart has that is hard to find in another player is versatility. He doesn't play any one position as well as you would like but he can contribute at 3 positions at a pretty high level.
He was picked in the range of Aaron Gordon, Exum, Randle, Stauskas, Vonleh, Payton, McDermott... None of these players are jumping off the page here. I am hanging in with Marcus. Marcus has a better shot than Rondo (I know, not saying much) but is more versatile. Is Rondo higher than Tony Allen? I think Smart is higher than either.
I don't think saying a middle class version (something better than "poor man's version") of DJ or Dumars is such a stretch. Those guys both averaged about 9 pts when they were 22. Marcus is not all that far behind but yes, he is trailing them at this point and probably won't match them. But these are stars of their time. it is a lot to ask for him to catch either of them.