This is a phrase I've heard bantered about recently. Tom Colicchio of Gramercy, Craft and America's Top Chef is fond of criticizing food this way.
I think I know what he means.
Meat needs to rest after cooking, right?, to let the juices absorb back into the flesh. But it's nice to have some juice still loose in the meat. The longer you let it rest, the less juice is available for the plate.
What the magic time between cooking and eating is, I don't know. It would be fun to come up with some kind of formula like: x degrees in the pan plus measure of thickness equals x minutes rest or X degree temp change?
The answer as to what perfectly rested meat is might be kind of subjective though.
What do others think?