I doubt there is a down time anymore between festivals, events, parties, free dining and discounts.
I am going in am month (the last few days of August) which have LOW(about as low as you can get) crowd predictions .. but I suspect it will be more crowded than predicted due to labor day being so late this year. (And going to MK on an EMH day)
The reason I chose August 26-30th? Super low crowd level predictions (which I picked from easywdw) .. (due to kids going back to school) ... value season (cheapest rate for resorts). Discounts were added to the trip AFTER we booked and we took advantage of those, but I am sure that encouraged some people who were on the fence to book during that normally "slow" time. Luckily my trip falls on the last days BEFORE free dining starts

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Personally I think that Disney does well with promotions and events to make sure the parks are crowded most of the time. Whether it is free dining or some special marathon or things like the Food and Wine Festival.
I would think it is hard to "predict" how busy the parks will be. Let's say you booke for a slow time and Disney then offered a 50% off vacation package during that time, wouldn't people gobble that up and make it as crowded as other times?
I would think the only time you could probably expect low crowd levels now is if you go in mid to late January where it may be too cold for some to want to go.