I believe him...we went to Magic Kingdom on a red non-
MVMCP party day in November that he listed as "AVOID" and he was spot on. We went in the evening for dinner at BOG and to see Happily Ever After and we were shoulder to shoulder. Every other day we went to MK on party days then hopped elsewhere and crowds were nonexistent.
We're going 9/28-10/4 so I still have to wait for the October calendar to be released but I was pleasantly surprised he has the 28th-30th as green overall when he had them as yellow in 2018.
I'm no expert on crowd predictions, but my guess is the switch in his weeks has to do with more people travelling the week of Labor Day and the week after because for years they've been "slow weeks." More people are following crowd calendars so those super slow weeks aren't as slow anymore. I still think the whole month of September will continue to be less-busy than other months because 1, school just started, and 2, fear of hurricanes cancelling vacation plans.