Kagawa has been injured, Welbeck is not a left-winger. I suspect we've also kept Welbeck as a back-up for strikers given we were without Rooney for a while. I don't deny it, points wise it is fantastic, and it could be a record season - I just don't see how that has much of all to do with Valencia. It's not down to him we have the points total, he's played a fairly insignificant part in that. He's not been in form and contributed much at all. I think it's as simple as this - had we had other options, like Nani and Kagawa available, I doubt we'd have played Valencia half as much. It's out of neccessity we had to play him, or we are pulling players from positions we can't afford to given the injury nightmare - i.e Young/Rafael...At his worst patch, we had to do exactly this.
I have no doubt Valencia will come back into his awesome self and hold down his place, but I can't see how you're tying Valencia's performances in the last few months to our current points total. It's not because of Valencia we have such a great position, which seems to be the point you are making. Generally, our wing play - both sides - has been so poor we've been winning in spite of them, not down to them. This isn't a 'knives out' approach either, I fecking love Valencia.