Haven't read the thread recently but saw it bumped which gives me a chance to get something off my chest:
To me, it seems quite clear that we rely on Paddy for our attacking shape. He does for us on the left what Alves does for Barca on the right in that he's the "winger" when we attack. He's the one that hugs the touchline and is prepared to beat a man and knock in a cross. Our left winger (between Young, Nani or Rooney/Welbeck if they're stretched wide) tends to be an inverted winger so Paddy tends to do a great job of keeping the width down that side.
In many ways, he is priceless to the way we attack, which is what makes him almost undroppable. For me, this is highlighted in who we bought as his back-up. We could've gone for most left-backs but we were rumoured to be in for Baines (who can swing in a lovely cross) and eventually went for a relative unknown from the Netherlands who -- from what I gather given the early opinions and obligatory YouTube clip -- gets forward very well.
Of course, playing that many games at such a high standard and doing so much work has definitely taken its toll. His licence to get forward, which I would say is probably less of a licence and more of an actual order, also doesn't help him be in a position to... y'know, actually defend.
All these things put together mean that I, personally, find his slight decline perfectly understandable. Given that Sir Alex keeps picking him it's not like he's going to say "Cheers mate but I can't, I fancy a lie-in", is it? Whenever I feel frustrated with Paddy I just recall all these things and it calms me down because I remember the factors that go into it. As far as I'm concerned, he's still the best left-back in the league. We United fans, as a generalisation, don't see much of Cole but I always feel he's a game-raiser. I have plenty of Chelsea friends (West London and all that) who moan about how Cole is "only" a 7/10 against poor opposition. I understand that this week Chelsea conceded the most crosses into the box.
We may moan about how Paddy's positioning is poor or how he looks exhausted but I reckon we've just become spoilt. Just my opinion anyway. He's definitely declined but he's still probably the best in the PL and it's not a huge decline, akin to Giggsy's.
(Not that I'm mocking Giggs or trying to scapegoat him, before anyone takes the point personally. I mean it from the perspective that Giggs is clearly declining in terms of what his legs can do.)