I'm pretty sure there's some more objective measures, like mile run times. There's charts for how long it should take you. There should be some more standard benchmarks for other activities.

I'd also like to suggest it's possible to be "mildly out of shape" and active. For example, if he was "out of shape" and recently started working out.

On the subjective lines, it's possible to be out of shape for certain activities due to the musculature you've built for the activities you do frequently. If all you do is bench weights, you'd be out of shape when you go to run a mile.

I'm like 8-10% body fat if I calculate it (electronic things say about 13%), would you consider me "in shape"? I wouldn't, not in any sort of normal means (running, lifting weights, whatever else).