1. Because they're Tarquin cnuts.
2. Because like the dippers they are congenitally unable to accept the new reality that City are a more attractive destination than themselves. In their heads it's still 1998 and St Thierry is still putting clubs like ikkle City to the sword in his sleep, and they can't wrap their heads around the fact that the sands of time have irrevocably shifted. That, and the Van Persie episode, is what underpins their idiotic determination to cling on to someone who doesn't want to be there. Think Pulp Fiction and Marcellus Wallace telling Butch to ignore the sting when the time comes to take a dive. "That's pride fucking with you", he says. "Well fuck pride." Trouble is of course, people like Wenger can't accept that.
3. As a result of 1. and 2. they will now engage in Operation Blame Deflection. By the end of this window they may or may not have sold Sanchez to us, but they will unquestionably have turned the lad into a greedy, grasping, traitorous hate figure, courtesy of their mates in the press. Raheem Sterling all over again.
Funny thing is I'm not even that bothered if he comes. Don't get me wrong, I'd love to have him, but if it meant we went after Dembele or Mbappe instead I wouldn't lose any sleep at all