How much DEC do you get in one chest, on average? I expect that all the DEC you are getting would be more than sufficient to buy the common cards and potions that I am getting.

I thought about that too. But not sure about that. My biggest DEC chest was 7k, and I had one of 3k. Other than that I think all of them were below 1k.

And by the way. I only had one GF (common or rare) and one legendary, so nothing spectacular. And a pack. And we are talking about over 70 champ chests (not sure about the exact number because I didn't track them)