So more of a gut feel than anything. That's fine, I thought it was something to do with Grubb specifically. Grubb's had success everywhere he's been. He has experience coaching basically every offensive position group in addition to coordinator, and was also a top strength and conditioning coach.
Although I don't think your hypothetical wager is that crazy, because it's true most coaches don't end up working out. I think Grubb has to be up there as the best realistic candidate we could hope for to replace KF. I'd be curious to hear your five names that you'd rather have (realistic options).