Anybody could do that, professional or not.I don't understand point one. It's walking half way down the pitch and kicking a ball 12 yards. How warm do professional football players have to be to do that?
But like you see in training, players always try to do personal ball training to warm up their touch, control, passing etc before real training starts.
For these professionals, going in cold IS going to have a negative effect, it's just a reality.
Edit: He should have subbed them on way earlier to get a feel for the ball and game, for say Sterling and Kane who were quite ineffective that game, especially Kane.