Answer Question
How can a tighter weave and more snug fit keep you cooler if evaporate cooling happens on the fabric surface?
Evaporative cooling keeps us cool when it occurs at the surface of the skin and so, one would think that a looser fit, more open knit would cooler but you note: "The microfiber polyester yarns are tightly knitted for the wicking sweat away and keeping cool on hot days."