Never heard the term "shift key animation".
The "stopping dead in your tracks" comment was about the other game where their new "skating engine" was faulty and patched after a few months iirc.
If you push multiple buttons simultaneously, you get different animations. Pushing in your right thumbstick and pressing your left bumper will allow your player to move laterally via the hipcheck animation. Any of the offensive skill moves like the lacrosse require you to use one of these button combos.
Unless, of course, you're using Total Control. If that's the case, you're putting yourself at a disadvantage against most WOC competition because you don't have enough control of your player vs skill stick.
IMO if you really want to get a handle of how you control your player, you should be running
hours in free skate with the pass aim visuals turned on. Mess around with the different animations. Try scoring lacrosse goals, through the legs passes, manual saucers and flip dumps. Mess around with different builds and find the ones that you like the feel of.