Habs fan here. Glad you guys like Diaz.
He was a polarizing player on the Habs board. Canadiens fans are so obsessed with size and toughness that they couldn't see what Diaz brought to the game. Before Diaz had to carry Douglas Murray as his partner, he was on the ice for the least amount of Goals against per minutes played.
Sure he's on the smaller side and isn't the strongest on his feet, but his defensive game for a bottom pairing D is quite good and the fact that he can move the puck is a bonus. I was sad to see him go, especially to play Murray and Boullion over him.
Hope he gets an extended chance in New York. If you can overlook his "softness" Diaz is good 5-6 guy with excellent gap control, an active stick, good position, an above average first pass and untapped offensive in him (though I don't think he'll ever reach his offensive potential). Sometimes he lacks poise and gets pushed off the puck, but all bottom pairing guys have their deficiencies and I think Diaz's pros outweight his cons.