I think you answered the question yourself. The lawyers crafted a story to help him get out of his situation. You really believe that is the true story? I don't.
The initial explanation from his agent would seem to be far more authentic. Why would he lie at that point?
Sure, it's plausible that Mizuhara had access to the bank accounts, but that doesn't really matter if you believe the initial explanation. I really can't get over that hurdle. Ohtani's primary representative, his agent,
knew about the gambling debts, the payments that Ohtani made, and he told us.
It's right there, they told us the truth right off the top. I've never seen a situation like this where people believe the backpedaling, without any evidence to support it.