He's never been as quick as Sane and has always run into blind alleys and lost the ball though. He's still a great dribbler but he's always overdribbled. Look at the stats, his dispossed stat is actually lower this year than all his prior years at Arsenal. It's just when he's on form fans don't care as much because he scores or assists. His form has always been patchy too.
The assumption was he was better last year because he scored more but he was playing as a false 9 last year with everything going through him. This year he's moved back out wide and like his first 2 seasons isn't as effective. And as a false 9 it hurt the team because the space in the box was vacant.
At United Mourinho will play him on the wing and he'll probably average 14 goals and 8 assists in the league each season. That's very good but is it worth 500k a week>?