Allardyce wrote in the London Evening Standard: "You can measure skill, you can analyse a player's endeavour and contribution but how can you really quantify what goes on inside someone's head?
"If I could unlock that particular secret, I wouldn't be a manager. I would be so wealthy, I'd be able to afford a yacht as big as Roman Abramovich's.
"Ryan did something similar on Wednesday against Olympiakos and it demonstrated just how much he has learned over the years because he never had that range of passing early on in his game. Then, he received the ball down the left side, dribbled past the opposition and either crossed the ball or got in the box.
"As time went on, he dropped into midfield and began making those killer passes - long balls - the sort which some say should have no part in our 'modern' game but are often still the most effective passes you can make if you get them right, as Ryan invariably does. There are some who believe he should still be playing every week but let's be realistic. He's 40 years old and just setting out on a coaching career."