He was discussed a bit in the next manager thread yesterday so I'll do a too long, didn't read version.
He's a promising young (36) Italian-German coach (born in Italy, raised in Germany) who came up along with Nagelsmann and the Stuttgart coach. Very tactical with his teams having 2-3 systems that they can switch between depending on the opponent or how the game is going.
He took Schalke to second place in the Bundesliga in the 17-18 season. His second season the entire club was a shambles similarly to us after the CL final and he got canned. But according to a friend of mine who support Schalke they talk about sacking him like we do about sacking Poch. He went on to manage Spartak Moscow in the Russian league and took them to 7th and 2nd place in his two seasons there.
Currently free after leaving Spartak. So he's had two decently big jobs at only 36 and done well at both.
Tagging
Paul Gascoigne
to this as well since he asked who.