As with all awards: they’re “credible” when you agree with them, and they’re “not credible” when you don’t. I’m guilty of thinking this way sometimes too, but it’s important to remember that this is mostly a fallacy.
I saw all 6 of those actors (the 5 nominees, and James MacAvoy), and it’s a really strong lineup. Personally, I might've put MacAvoy in over Jesse Tyler Ferguson and Ruben Santiago-Hudson, but that’s because I’m actually in the minority; I wasn’t as enamored with those 2 performances as most people.
And actually, even if those 2 actors got kicked out, I still would’ve put in Bill Camp, Laurence Fishburne, or even Jasai Chase Owens (Sanctuary City) over James MacAvoy,
But obviously the popular opinion is that Ferguson and Santiago-Hudson deserved recognition, and IMO Dirden, Ming-Trent, and Thompson all gave exquisite performances that deserved to be nominated over James MacAvoy. So in my mind it’s “credible,” but obviously it’s all just completely subjective.
And I’m not even saying this to bash MacAvoy – I thought was very good!
Out of the 150-ish nominations, I think there’s only about 20 or so that I didn’t see – and while there are some things I would’ve changed if I were the sole nominator, these nominations still seem perfectly reasonable to me, based on what struck me as the most deserving work of the season. But again, it’s all subjective.