Bipolar disorder manifests in different symptoms for different people, even splitting into Type I and Type II within the diagnosis itself.
Not being familiar with Gregory’s personal life and what he is experiencing, I would say that the trouble he has experienced is more related to substance addiction and the aging rules of the NFL rather than Bipolar disorder.
Most likely he’s self medicating the depressive episodes of bipolar disorder, so it’s kind of a war on two fronts. It’s traditionally hard to treat those dual diagnosis mental health/addiction situations.
At least that’s my incredibly superficial assessment from halfway across the country via the internet. Either way, I hope he can at least contribute. I would be happy for him if he could, but the team is in trouble if they’re relying on him to be a cornerstone. Not because of any diagnosis, but he’s simply an aging player without a lot of experience at this point.