Improved- yes, but not to the level of most starting PG in the league.
Same goes for Rozier.
The thing is, we don't need him to starting PG ball handling; although it would certainly help Smart in his obvious offensive deficiencies. But he's been better at making smarter plays, and been niftier in pick and rolls. He made some amazing plays, along with that spin and ol' English finish.
Reckon he workshopped with Kyrie? Saw him do a sick spin into layup-with-english as well! :]
That's my guess as well, along with a more defined role and more minutes, it's pretty obvious that Smart has finally been able to play in a role where his main goal is to defend, play make, lead the team, and literally make the other team's night a living hell.