Marcus Smart is one of the most pathetic shooters in the history of the NBA. Nothing has changed.
The difference with a 3 and d shooters is that those guys can shoot the 3 ball , they can actually make 3 pointers.
Which brings me to the key for the Celtics in the playoffs.
Marcus Smart is left open / given the shot most of the time, a good 3 and d player would hit an open 3 at 45% clip.
If Marcus can hit his 3 point shot at 35% during the playoffs , given that he will almost guaranteed be left open while focus is on Kyrie and the other guys, the Celtics will be golden and probably finals bound.