BVB are not a counter-attacking team under Tuchel; infact, they are quite the opposite. They play possession football like I thought we would under Van Gaal. Possession football with the ultimate aim to score, not to keep the ball for the heck of it. They had pace to get behind defenses and took risks in the final third of the pitch. The build-up approach was more measured than Klopp's run and gun style, but they were very effective with the ball when it mattered. They were quite pleasing to watch.The closest comparison I can make is to a Wenger team on a good day. (I have a bet with an Arsenal friend that Tuchel would eventually succeed Wenger).
As for Mkhitaryan, I have the same concerns as you. He doesn't look that special a player to me. The stats people bring up from last season are the similar to how, I am guessing, they would have been brought up when we overspent for Mata a couple of years back. Mata had similar crazy numbers in his last season with Chelsea. Players can have an individual season or two that are complete outliers from their overall career. I, personally get a serious Mata vibe from Mkhitaryan. A good player who has the ability to be world class on the day, but doesn't have the personality or the game to be a categorized into a world class player.
The only way this signing makes sense is if he can price him away for under 30m Euros. Kind of a low risk punt.