This is from CBS Sports' Zach Harper:
Since the NBA started caring about players shooting quality shots and not just chucking anything and everything like they did in the 1950s, Marcus Smart is the worst shooter in NBA history through his first two seasons. He has the lowest field-goal percentage (35.7) ever for a player in his first two seasons (with at least 3,000 total minutes) and he has the lowest true shooting percentage (47.6), as well.
Yikes. Out of 218 players with at least 400 attempts last season (roughly five per game), Smart finished dead last in field-goal percentage at .348 (184-529). He actually regressed from his rookie season, during which he shot .367 (175-477).
Overall Smart's numbers were very similar from his first year in the league to his second, which is why he cracks Harper's list (the article linked above) of guys poised to break out in their third season--the Celtics "just need him to no longer be historically bad at making shots."
I wrote this for CelticsLife in March, making the case that his shooting should improve:
How worried are you about Marcus Smart's terrible shooting lately?
A year ago Smart dislocated two fingers on his right hand while playing in summer league, which cost him a chance to spend the offseason working on his jumper. No excuses this time around.