It’s quite insane how young he is. I wonder how he got this far this fast
Short version:
A perfect storm of ability, opportunity, and being heavily influenced by Pep & Tuchel (before Tuchel had gotten so conservative) as he made the jump to coaching.
Longer version:
Injury ending his playing career so early was probably the big turning point. He wasn't a superstar prospect or anything, but he was an extremely intelligent player and had some hype as a member of 1860 & Augsburg's academies before his knees gave out. That helped open the door for him to immediately get a job as a scout for Thomas Tuchel, while he worked on his coaching certificates...where he really flourished & built on his hype.
He's brilliant tactically and regulary tries the type of things that I lament other coaches not even attempting*...but arguably the biggest factor in his success has been his ability to connect with players and I think his youth helps with that; though he is also reportedly super-charismatic & personable, as well as having more in common with his players than most coaches.
*something that may also benefit from not having another decade of other coaches drilling their ideas (and limitations) into his head as a player