Thanks for the responses guys :thup:.
I suppose I would call it a mixed bag of results. More peope than I had expected seem to be finding that this works ok, but only 1 of you found that it worked where a full back was defending a winger, (and it only worked in that instance where the tactics were specifically designed to aid it's working).
Like a lot of new features that are added into the game, it seems a good idea that has been poorly implemented.
The crux of the problem is that I don't want my full backs to show the opposition wingers the outside at any cost. I don't care if the winger comes inside and smashes the ball into the corner past the hapless keeper. I want some evidence that I am controlling what is happening on the pitch. I'm not seeing it at the moment. I have watched full games with various defensive lines and various width options and have seen very little evidence of this happening more than sporadically. I thought that closing down would impact on this, but the closing down issues themselves, (or a mixture of the closing down and positional issues, (whatever they are)) seem to make any real evidence null and void.
Obviously as others have mentioned, playing with a deep defensive line, (and width) encourages this to happen on a more regular basis, but still nowhere as often as I would like.
I am trying to create an environment where my full backs will position themselves goal side of the attacking winger, not give him the option to go outside, and force him inside to where I have a packed midfield. The way i look at it, if I set closing down to high then I risk the defender getting to close to the winger and having him "done". In real terms I would ask the defender to "stand him up", not committ himself and either let the winger cross from deep or come inside. I am prepared to deal with the consequences of either of these as at least it will mean that 2 players on the pitch are attempting to follow my instructions. What I am finding is that it is impossible to replicate this on a regular basis.
The main crux of the problem apperas to me that my full backs seem to think that the best position to be in when about to pressure a wide attacker is "inside" him rather than "goal-side" of him.
No amount of tinkering with width/closing down/show onto foot seems to affect this when faced with a wide attacker

.