Player level is 100% irrelevant. Ignore it. It means literally nothing.

Team power is deceptive. As you get more experienced you'll learn how to interpret it better. That said, an enemy with team power of 60k is almost certainly a very weak team, especially given they are running level 50s. If your debuffs landed and you still did no damage to them, it's likely due to one of two things:

1. Your nuker was the wrong affinity. Weak hits have several negative effects applied to them - they cannot be critical, which further means all your crit damage is useless, and on top of that, they do reduced damage. It's very possible that you normally do 50k+ damage on your nuke, but only 5k damage on a weak hit.
2. They were running Reaction set items, which means they have a chance of turning a critical hit into a normal one. But, given their low team power, my guess is it's probably #1.

This could be so many different issues. I like Krama's assertion that it likely could be an affinity issue. Getting 3-4 weak hits happens more often than you would think, when you start playing a ton of arena. 

If you have a picture of the results screen, we could make better guesses as to what it could have been.

I know this is rather old, but thanks for pointing out the 'weakness' issue.  

Old or not, glad it helped. :)