No one is going to come out and say "My name is [Player X] and Kyler Murray doesn't do the work." Not only is it deeply unprofessional, but the NFL is a brotherhood, and that would be a deep betrayal of the lockerroom.
If your standard of evidence is that Larry Fitzgerald holds a press conference and says, "Man, everyone in that building decided that Kyler is the new hotness as soon as he was drafted. He was allowed to write his own ticket, and it set a bad example," you're NEVER going to hear that.
You have to trust that these blind items are legit and that national beat writers don't have a compelling reason to conjure fake news about one of the five least-popular teams in the NFL [Citation Needed].