Maybe it's my ignorance to what Captain Sobel was like in real life; but after reading the BoB book, I felt like Schwimmer nailed the character. Sobel from my understanding was petty, sadistic, and power hungry. What exactly did people not like about Schwimmer?
Schwimmer was incredible in this. If people really are just saying they didn't like him as Sobel because he was on Friends, and they find it distracting, can't separate him from Ross or whatever, then they're idiots.
He played the role so well that he embodied Sobel. I remember some of the real men of Easy company who saw it said this. That's an actors job, he is not Ross, he is Sobel. Ross Geller is irrelevant.
I found him pretty good too. Especially his reactions when he gets shunted to the jump school and his pettiness later on when crosses paths with E Company.
I actually watched BoB AFTER watching Friends for years (infact probably after Friends had ended), but he still made me totally buy into his character as Sobel and never felt I was watching Ross in uniform. Impressive tbh.