I looked at his stats. He really has only one season, 2029/20 with BKN, where he was better than Smart. And even in that season, where he did score 20.6 ppg, he needed 16 shots (not great efficiency) and over 30% usage to rack up those points. His shooting percentages, 41.5 FG%/30.8 3P% were actually no better than Smart.
I doubt this guy gets the kind of money he is fishing for but whatever he gets, to what extent does this set Smart's market? I am not sure I would want Dinwiddie over Smart, certainly not on this current Celtics team. Is a high volume, shoot first PG, coming off an injury, with a 30.8 3P% really something teams want to pay big money for?
People are assessing Smart as not good enough the be the 3rd best player on a good team, more suited to be the 4th best. This is probably true but isn't it also true for Dinwiddie? The Knicks for example (a team with some cap space), how good is a team headlined by Randle, Barrett, and Dinwiddie? Better than Tatum, Brown, Smart?