Speaking from experience...it is not overrated. I grew up in Miami and played college basketball in Pennsylvania. When I came home for Christmas break and went to the park to play a little bball with my friends I was keeled over in the first 5 minutes gasping for air. I felt like I was suffocating trying to get air in my lungs. The humid air is thick and that was December. The heat isn't what gets you...heat I had no issues with, it was the humidity that tore me up.
Sounds like my story. I grew up in south Florida and went to college in Philly for 7 years, and returned to FL after. I still travel back and forth to cold weather areas often. I can understand the heat advantage during the Summer, but in mid-October that advantage is long gone. During August and September, is was 95 degrees with a heat index of 105. Its now 85 degrees now with a nice breeze. I doubt it affects players much in October.