Through the first three rounds of the draft, the Leafs are seeking out size. Auston Matthews stands at 6'2", Yegor Korshkov is 6'4", Carl Grundstrom 6'0", Joseph Woll 6'3", and now J.D. Greenway at 6'4".
Greenway is a hulking left-handed defenceman who comes from the US National Development Program who already weighs 205 lbs., but that doesn't mean that he doesn't have some offence to his game as well. Last season, Greenway picked up 28 points in 64 games, and also had 7 points in 7 games at the U18 junior tournament.
His draft rankings, according to Eliteprospects, are mostly lower than where he went (with a few in the 100's) but then, some pundits had him going much higher. Damian Cox, for example, had Greenway at 23rd overall (which is way off the board).
SB Nation's college hockey site has a profile on him and had this to say: