I am a commissioner in a 12-team 40-man roster 6-Minor League spot Otteneu league so there's a ton to keep track of and I do my best. Needless to say, some things slip through. My two cents is that the guy that originally drafted the player did nothing wrong on his end and should not be penalized - he should still have his drafted player on his roster - this goes in line with what you have already said, so I am just confirming your own actions. As far as the other owner is concerned, I would not allow him to be able to claim anyone he wants for $1 - simply b/c it is not fair to the other owners. Where would it end? Do you allow ALL owners to make a free $1 claim? And if so, who would get the first claim? It would be a mess. In this case, you just apologize for your mistake and gently remind all that being the commish is a ton of (thankless) work and in a complicated league format, mistakes will happen. I would even go as far as to say that in the future, it is incumbent on any owners making a claim in this period to verify that the player they are claiming is not currently on a roster. In these cases, I will sometimes ask anyone in the league would like to volunteer to manage the specific portion of the league in question. Usually that gets them to think about the work involved in doing that and prefer to keep their mouths shut about it. Good luck!