I don't think this is a problem with the matching system. The other player is declining the battle. Your wizard wouldn't happen to be balance, would it? Mine is a high level, high rank balance and this happens to me a lot. A lot of players (those who have not invested training points in tower shield) will decline battles with balance.
They log in under a separate account and watch the 1v1 matchups. If they get paired up with balance (which they'll see after you've accepted), they'll decline the match.
Before we get any further can I please make it clear that I am not complaining about who I get matched up with in the arena... if only I got that far!
Most of my night is spent clicking on the GO TO ARENA button only to find that my match has mysteriously disappeared, over and over and over again.
Please fix this, it is tedious and boring, I shouldn't have to spend 30mins or more clicking on that darn GO TO ARENA button just to get one PvP match.
Honestly I don't care who I battle, I just want to fight!
While your wizard is waiting for their matchup, they are free to do other things. So if someone chooses to do a quest while they're waiting and get into a battle, the decline allows them to continue with their quest (or at least finish that particular battle).
On possible solution would be to make the match system "blind" until both users hit Accept. That way there's no way to see who you're matched up against until you actually enter the arena.
Sounds like that is what is definitely happening to me, and I can see a very simple fix... remove the decline button.
If the intention of ranked matches is to provide random opponents rather than letting wizards choose the battles they think they will win, what purpose does that button serve?