Let's just say 'Math' isn't the most important subject in Cleveland.

Even if the win percentage was
10%, it's still much higher than the likelihood of guessing the exact yards of a passer in a given game.
Like.. your example was Stroud throwing 250 when the line was 245
Even if you know the final passing yards were definitely going to be +/-5 from the line, that's a 9.09% chance of guessing the right number...
The real likelihood of guessing the right number is much lower because obviously there's no guarantee the actual number will be within 5 of the line, just an example for you to see how wrong you are..