This is accurate.
If the Bills lose 2 from category 1 (which happens, it's the NFL), 2 from category 2, and lose to the Chiefs, they go 11-5. To me this seems reasonable and it means that between 10-6 and 12-4 covers probably 75-80% of likely outcomes. 9-7 and 13-3 are both possible, but more like 1 in 10 chance of happening either way.
But this is why they play the games...