Sure, he touched the ball but that touch didn't put the ball far enough from Arnautovic for the subsequent action (taking him down) not to have been relevant.
Slide in like that and get enough of the ball that it goes out of play or to another player and it's fine as what happens after the touch isn't relevant (as long as it's not violent conduct).
Slide in like that, just glance the ball as he did, then take out the player that could have run onto it had they not been taken down = always a chance of a penalty.
Just touching the ball doesn't excuse any subsequent actions. In that respect, it was a sloppy tackle.
Sure, he touched the ball but that touch didn't put the ball far enough from Arnautovic for the subsequent action (taking him down) not to have been relevant.
Slide in like that and get enough of the ball that it goes out of play or to another player and it's fine as what happens after the touch isn't relevant (as long as it's not violent conduct).
Slide in like that, just glance the ball as he did, then take out the player that could have run onto it had they not been taken down = always a chance of a penalty.
Just touching the ball doesn't excuse any subsequent actions. In that respect, it was a sloppy tackle.