[bfk]

We noticed this too. Older balls have little breaks (or in one case a 2 inch tear) in the outer skin which allows air to escape, thus decreasing squishiness. Not sure what we can do about it. We thought of shining a light on the balls in our ball lifter and using shininess as an approximation of squishiness, but haven't done anything yet.
It was pointed out by others that the balls in the competition are unlikely to be new every round, more likely that the most beat up ones will be replaced as needed. This will probably lead to most of the balls being a bit chewed up, with a few new and a few on their last legs in each round.