Tournament Matches -- I have no idea how matches are determined

I don't know if something has changed in the way matches are determined, but I've been getting some rather random matches in the Deck Wars Black Card Tournament.

First of all, I sometimes get matched with Level 1 decks. These still earn the minimum 4 trophies per match (plus 4 for streaks for a total of 8), but it's kind of odd to be matched up with them, as my hero is Level 3. In fact, how is it even possible for a Level 1 deck to exist, especially Finn or Jake? My guess is that someone didn't finish the tutorial and immediately started playing Deck Wars before leveling up the heroes to Level 2, which you normally do within the first 6 Quests.

Needless to say, beating a Level 1 deck is pretty easy. There are usually two open lanes where you can place 5 ATK cards, knocking the opponent from 15 down to 5 points. Then the opponent, who already has a weak deck, typically uses Mouthball and stupidly floops it, leaving you an open lane to finish the match.

But I've also been getting some Level 4 or Level 5 matches. These earn more trophies (7 trophies in this case). They're a little harder to beat, but with a decent deck, it's possible.

 See?

My next match was very strange -- a Level 14 deck for 10 trophies! But Level 14 heroes have 80 HP, so this is almost impossible to beat with my weak Level 3 deck.

And of course, I lost. Even if I had been able to make a few more hits, I would have quickly run out of cards.

After that Level 14 match, I was matched up with Level 1 and Level 2 decks again.

So, to summarise, I have no idea how Card Wars determines matches, and from what I can tell, they are often mismatched.