That's because you aren't willing to say this idea that first rounders need to be special is a narrative that you've created for yourself and you're clinging to.
We don't have a lot of info on how BB picks RBs but this is what we do have:
View attachment 28750
So he's looking for a tough inside runner, ball catching, blitz pickup, blocking, overall intelligence. Note he doesn't talk about "burst" like so many here say, or "elusiveness". He even says
NOT HAVE TO BE A RUNNER NECESSARILY. He's just looking for good overall football players that can fill roles. If one happens to be "special", be it in the first round or the sixth round or UDFA, so be it.
You're the one that raised this specialness needed by first rounders thing, it's on you to show it exists.
You don't seem to have a good grasp on what they look for in a RB and you certainly don't know what their opinion of what he's doing relative to what they expected from him is.
Let us know when GMs are issued time machines so they can go back in time and do things all over again. Till then this is a nonsense statement.