Yes, he was definitely one of the better coaches in MLS when he was around. He won the Supporters Shield in 2015, won the East in 2016, and had the team humming in 2018 before he left (they eventually won the SS and achieved the highest point total in league history).I'm sure the germanic origins of his surname helped him considerably, even if he's as culturally American as most of us here are.
Congrats to him, that's no third-division backwater. But was he really regarded as a top coach even at MLS? Coach of the year in 2015, but a lot has happened since then.
He hasn't passed what I'll arbitrarily call my "Jason Kreis Test": can he be successful with two entirely different cores? But he hasn't failed; he just didn't spend enough time in NYRB to have to fully turn over a team. That being said, he was able to continue to be successful despite the club shipping out major figures like McCarty and Kljestan in successive seasons.
If the RB organization didn't think much of him, they wouldn't have brought him over to be an assistant in Leipzig or give him the Salzburg job.
I think he would have been a more serious contender for the USMNT job, but he is on bad terms with the federation and moved forward with the RB Leipzig assistant gig as the process was (very slowly) unfolding.