I'm currently in the army, and I'll say that across the board the standards are ridiculously low. The average soldier is a fucking moron, weak, slow, out of shape, selfish, and a shit bag by even civilian standards.
That being said, you have to put that 40 minute run into perspective. Rangers aren't specialists. These are guys who are expected to be able to carry a 50-60+ lb rucksack a pretty serious distance, while also wearing 40 lbs of body armor and ammo/gear. They're also expected to be strong enough to carry their wounded comrades, wearing same amount of gear. They have to be a blend of stamina, speed, strength, and technical and tactical abilities. If they're able to run 5 miles in 30 minutes, there's a good chance that their other physical abilities are going to take a cut to make up for it.
Again, I hate the army, it's pathetic how fat and out of shape 90% of the soldiers are. Soldiers are nothing like what the media portrays them to be, or the average civilian expects, so take it for what it's worth.