No one doubts what Özil *could* bring to the team, even in a 5 minute burst - the problem is you can never predict when he’ll be available.
Seriously, how can you ever make any plans around a player who won’t play away games and who you know will randomly miss every other home game through “sickness” or “back problems”? Why waste all week coming up with a game plan, and months trying to implement a style of play, when you know that there’s a 3 in 4 chance that your key component won’t show up? Özil probably has more talent in his little toe than most of the players in the league, and yet for all that he’s still less valuable than a player who actually shows up.