I was passed by Matt Tegenkamp once on the Springwater trail. I was out doing somewhere between 16-18 miles; he was effortlessly jogging with a partner at probably a 6:00/6:15 pace.
I considered catching up and sticking with them for as long as I could, but it would have trashed my long run, and probably annoyed him, so I let him go.
The dude was like one tall cord of muscle. Impressive.