TEA doesn't make estimates. They ask the theme park companies how many guests they had, then they publish the numbers.
As I've pointed out before, it's been said that as a favor to Disney (because they're the 800 lb gorilla of theme park companies), the numbers reported by the other companies are collected first. Then they're shown to Disney, with the request, here's what the other guys said, um, please sir, what are your numbers for the year?
I don't think that Disney is flat-out lying about their numbers or faking them, either in what they report to TEA or in what appears to be the crowd levels at a time like right now, when people are reporting anomalously large crowds that are inexplicable for the time of year.
Here's what I actually think Disney is doing. Speculating from 2000 miles away in a state of nearly completely ignorance:
I think the numbers reported by Disney to TEA may be massaged, torqued and/or manipulated and stretched to make DHS, AK and even Epcot look like less of the red-haired, jug-eared stepsisters that they are. I think they do this by distributing park-hopping days to make the non-MK parks seem more popular than they are. And I think that they might also be counting unused, expired Magic Your Way days as "visits" to whichever park they think needs some statistical love. Maybe. I don't know. It might explain why a relative dog of a park like DHS "beat" a beauty queen of a park like USF in 2014. By 25% ??? That's a LOT of Star Tours rides.
As for this autumn - I don't think that Disney set out to create fake crowd levels. Either they are getting a ridiculously big surge in attendance ... for reasons that totally escape me, after checking out the stats for real household incomes (falling more or less steadily since 2000) and retail sales (precipitous). Or else, BECAUSE of these precipitous numbers, they are cutting back on - let's call it "guest experience" - not in order to build a case for price increases, but because they think that the cutbacks, PLUS the price increases, are the only way that they can maintain profit levels during what appears to them to be a deep and worsening financial downturn.
I speculate.