I am amazed how people can watch the same game and come to such differing conclusions (I suspect that confirmation bias is at play). What I saw was Smart clearly making a bigger impact on game 5 than Rozier. On the offensive end, the offense ran better when Smart was in control. The ball got to where it needed to go and when he took his shot opportunities, he converted at least as efficiently as anyone else on the court.
But his real impact came on the defensive end. He was sagging, switching, manning up, doing it all. He had an impact on every aspect of the team defense when he was on the court. You have to watch to see how many times it was Smart that rotated to either double or get back to an open man. He was the guy that was reading everyone else, identifying the soft spot, and closing down where it was most needed.
Far bigger impact than Rozier in this game.