In my honest opinion, there is no better player for bringing the ball out from the back, or moving us up on the counter, than Valencia. The problem is, when he strays too far forward, its like he has a BSOD and his footballing brain shuts off. If our attacks went through the middle and our build up play was incisive instead of slow and laboured wing play, he'd be a good enough asset because he does play the ball into one of the forwards on the edge of the box. When he plays our team uses him as a focal point for nearly all of our attacks and it's the same with Young when Valencia doesn't play. You're asking semi-mediocre players to be the inspiration for our attacks. It's just not going to happen. This is what frustrates me about some fans. They're quick to write off the players who aren't as good as the others, but the truth is when you have Carrick, Rooney, RVP and Mata on the field, you shouldn't rely on your RW to supply your attacks...
To summarise, he's been no worse than our other attacking options this season, and he still offers a lot defensively and links up well with everybody. Should he be a regular for United? Not really, but the truth is we have nobody else who is streets ahead of him in attacking sense, which could justify losing his work-rate and defensive aspects.