PSA: Don't play Yahoo Pro Leagues
Context: I've been playing Yahoo Pro Leagues 10+ years and historically I found them to be pretty good non-bias commissioners and payout managers. Unfortunately it seems as far as fantasy basketball is concerned they care, less and less. They had this trade approved. Which you may not consider vetoable until you consider the fact that these managers compete in the same pro leagues and are only trading between one and other, where the clear losing side of trades is the team eliminated.
It's textbook collusion, but Yahoo doesn't give reasons behind their decisions. Additionally they've been noticeably late responding to league protests or giving INJ tags this year. I'd discourage anyone who is considering or currently playing on Yahoo not to. As someone who has been a customer for over a decade.