Honestly, I think it's about clicking and holding it at the perfect time. I seem to get a lot more speed when I click it after I've reached the default max speed. I hear you though. EA said skilled forwards would basically always beat a defense yet it seems random and most of the time the defenseman comes from behind and passes me.
There are grinders with 95 speed and just about no other athletics. Its best to knock them around if you encounter one.
Very annoying but fun to knock around. Another thing with the speed bust is wait till you at top speed to use it. Maybe just me but I didn't see clicking it rapidly do anything. Gliding makes a big difference to