No Sanchez is an interesting call by Wenger. However, I can see the reason behind it both tactically and as a signal.
The ball tends to stick to his feet. Always wanting to turn and make something happen, which plays right into the pressing game of Liverpool. Obviously, he tends to make something good out of it, but it is definitely not a good trait against a team like Liverpool.
As a signal, it shows Sanchez and the unavailable Özil that they are not above the team and that the club can and will function without them.