If the rating was for both decks you beat and decks you lost against, you would thumbs up every deck you beat to keep it around longer.
Meaning that if I was to grind with Black Holes, I would thumbs up every speedbow I beat, because, free money!
This was is good. I don't rate on the quality of the matches, I can have a great start, they can have a terrible start, whatever. I rate based on how original the deck is. Meaning, I have never given a thumbs up to a: GotP Nightmare/Speedbow/Oraclebow/Firestall , and other decks which are too chiche.
"Besides a Fate Egg deck who enjoys losing?". Flying Pulverisers, Crusader Arsenics, Mitosis Scorpions - anything that is different and original, but works well. The kinds of things people should be making with the arena cards given.
Oh, and I will almost always give a + to a deck using the ability of Schroedinger's cat, Aflatoxin or Sky Blitz. (Non rainbow stall extra cards, actual strategy cards)