Do you think there an underlying issue with Sanchez that we're all unaware of? I say this because I can honestly say I've never seen a professional footballer (or any sports person for that matter) exhibit such a rapid loss of skill or ability. Generally a person's skill level declines over a period of years, but not weeks / months as is the case with Sanchez.
It's quite staggering how quickly he has regressed. How can anyone with so much talent get so bad so quickly.
There must be a logical explanation behind this. I know this sounds weird but from a purely humane point of view I'm a bit concerned for the guy.
His best season was 6 months before you signed him where he netted 30 times, assisted 13 times and 12 man of the match awards. He played as a false 9 for most of that though. When it was apparent he was leaving he was moved back to the wing but still managed 8 goals and 3 assists and got 3 man of the match awards but he seemingly seemed like he wasn't trying.
The thing is though throughout that time when he was in form he would make loads of braindead decisions. He'd always overdribble or pass to the opposition constantly. But the goals and assists made it forgiveable.
Wenger also allowed him loads of freedom and would commit all of our players in the opposition half pretty much. This meant Sanchez was pushed further forward towards goal and he had more time, space and players to link up with. When he left I said 'he won't play the same under Mourinho'. Then watching a game where he's dribbling in his own half I knew he wouldn't work being so far from goal. If he went to City instead he would have done better. Pep managed him before and knew how to get the best out of him.
So yes he is past his physical prime but the goal he scored against us (arsenal) showed he does still have something left imo. He just needs to have a team built around his strengths.