What's up with those Tights?

Why are some players wearing full leg tights? Is it for warmth? better vertical? looks?

i think its just support, cuz u dont need to be any warmer then your gonna get and u know it wont help your vert in anyway

They act as a venous return mechanism.

I think running around the court will give them all the venous return they need.

Yes, but not during time on the bench/timeouts/between periods etc.