Santi is a very unique player, few players in the world have his skillset. I always prefered him at no10 to Ozil, I think he's a more incisive player than Ozil and he got shifted out of position after Ozil's arrival. Pushed out to the left wing and then to DLP.
After he got injured everyone appreciated what a good job he was doing. But when he was a midfield controller, keeping possession, dribbling through the opposition when pressed, spreading play and creating from deep everyone complained. I didn't.
Despite playing as a DLP in 15/16 before his injury he'd created the second most chances in the league, second only to Ozil who played further up the pitch. His range of passing, his accuracy and decision making is second to none as is his technique.
Ironically he'd probably be even better in the 3-4-3 with 3 centre backs covering him.