I am getting confused and you are criss-crossing topics. One moment it is about the flaring in the leg opening and the next it is about proportions and then being taller?
It isn't the flare that makes them look tall, it is the whole cut from the skinny upper of the pants/jeans to the bottom flared out. It creates a shape, an illusion that a person is taller. Actually, it is more the skinny upper of the pants, taper those pants and he would still look taller.
Also, there is a big difference between these two. One is cut boxy and square while one is skinny up top and flares in the bottom. I am pretty sure that if the guy from SF make his pants slim like that, he would look extra tall too.
Proportion-wise, it still isn't consistent to me, the straight leg jeans just looks blah and square. Get a bit of taper and get rid of the slight flare and it'll look better. And as you said, the waist to hip ration of the jacket "matches" from the knee-down, again that is matching, not proportion. It doesn't really balance it out in my eye especially since the jacket flare is much more pronounce than the flare on the leg opening which was barely noticeable and chances are non-existent if he stood up straight and aren't moving.