It is value season, but also
free dining now (if it is offered again this summer). With free dining the value resorts fill up quickly...anyway, I'd rather be wrong and get there early with a better chance of a good room location than the end of the day and the picks are slim!
For 30 years we went the end of August and although it is not as busy as July or early August, it is still busy. We were there last Auguest, exactly your dates and it was by no means slow. The POP food court was the most crowded I'd experienced it in our 4 stays there.