Think Robson-Kanu's problem earlier in the season was that he was waiting for the defender to commit himself before doing anything, or just trying to run straight past him with by tipping the ball forward and sprinting whilst close to him.
That slows down his play and gives the defender the chance to set himself and it makes it harder for him to move the ball around a challenge, or just makes it too easy for the defender to stick out a toe and knock it off for a throw.
What he did so well yesterday, was force the issue with a good switch of pace or direction. He was forcing the defenders into commiting and therefore able to predict what they'd probably do and go around them.
For me that's the difference between him being a League One player and a good Championship winger. And his scoring record is pretty good for an inexperienced winger. He doesn't score a lot of great goals, but he's does find the net and that is all that matters.