I assume based on the scoring structure in the NFL that WP numbers aren't very linear across various lead amounts. There is probably a noticeable jump in average WP across any time swatch in a game from being up by 7 to being up by 8.
Not sure if that makes sense but what I'm trying to say is the 8th point is worth a lot more than coaches realize. Because it's not easy to get 8 points on one drive, and number of drives is relatively finite across the game, so if you can do that and your opponent can't, you are exploiting a huge edge.
Also it is amazing that they won't let CAM go for 4th and inches. Far too often these coaches fall into the "but they are expecting that! We'll never convert! It's too obvious!" mentality when sometimes brute force is all you need. Even if they expect you to sneak CAM..