Found this on OS regarding the quick sub menu
I'm still at work so I haven't tried it but this seems to explain it better
OK, I figured out OTF Subs. Down on the D pad brings up your players on the floor now you must use the right stick to the corresponding player you want to sub out The Point Guard is up on the right stick. It sends you to the players on the bench that can fill that role. Now select one based on the right stick direction press circle and he starts to walk towards the Press table. The Manual doesn't go into detail at all, just down on the d pad follow on screen display. That's literally all they say.
I'm still at work so I haven't tried it but this seems to explain it better