I don't understand how Tuchel is rated so highly
I agree, but he's on the managerial merry-go-round, and now that Pochettino is employed, Allegri and Tuchel are the next two due to be linked with every struggling elite team.
He turned Mainz from a shithouse to a Bundesliga mainstay (following Klopp) and turned Dortmund around after Klopp's dissapointing exit (7th). He also left PSG with the best win record in Ligue 1 history, so the reason he's highly rated is because he's done very well in all his jobs I reckon