Where they played ball last year means nothing. Every year, it takes time to acclimate. As a southerner, personally speaking, the first 90 degree day of summer can be miserable. By the time September gets here, 90 degrees is relatively comfortable. Varied with humid vs arid days, and it's a whole new equation. Had they just been through training camp in 100 degree weather in Boston?
My point is, just because those guys have played in those conditions in the past does not mean they are prepared for it now.