90% of the time there is too much variation in their evaluation simply based on if one call in a game was seen as "bad" (right or wrong) and if they win or lose the game.
You could have a crew that went out and yucked it up with a coach, were sloppy mechanically, and as long as there weren't any big plays or tough calls and the coach wins the game they are going to get a 1 or a 100, or whatever the top grade is.
Now you take a crew that is all business, but not aloof, great mechanics and have one questionable call (right or wrong by the crew, doesn't matter it is the perception of the coach) and the coach lose and they are going to get downgraded, most likely.
It is the nature of the beast, they don't know our mechanics, they don't know what different officials are looking at, and many know only a smattering of the rules, work the wings and hear a coach ask questions about one thing or another and it doesn't take long to figure these things out.
So the ratings/grades aren't really worth much except to make them feel like they have input on something, if they really feel you did a bad job, they will scratch you and you can go on and work the multitude of other schools that every chapter services.