Yeah, as with everything else, you need to consider the context.
It also doesn't account for sacks, which is fine, since it really just wants to grade the passing aspect. I feel like they could probably incorporate coverage sacks into the score. I assume they have enough data to do so. While coverage sacks are a credit to the defense, they're also an indication of the QB making a bad decision, whether it's missing a read or holding the ball too long.
I do like the way this is presented. I can look at it and easily tell if Allen passed the ball well or not. Then just look at the box score to see what else happened.