I'd like the shirt to be an inch loser. It should have a little room to breath properly considering the weather. I do agree that he has yet to look uncomfortable in it. It's just my personal choice. I typically wear loose stuff in the summer.
Emma Jean, I found this on the adidas website with regards to the barricade clothing worn by Andy,
'Each style in the collection uses ClimaLITE® technology in specially placed mesh zones for maximum ventilation on court, ensuring your body temperature is at optimum level even during the most intense rally.'
Although that quote relates to the ladies clothing, the mens will be made of the same material.
It's all pretty technical stuff just for a piece of clothing, but I'm with Angie on this one.