Not a guy, but a girl at my HS, ran cross country 1 year, ran like 17 something in the 5K and won regionals I believe. Then she just stopped running, no track just 1 Cross Country season - my track coach was obviously pissed. She beat a girl on our team going D1 multiple times. She just wasn't interested.
She was like Parker Valby was thing, did a ton of cross training on the elliptical. It was unreal to watch. I don't even think she did summer training with the team and didn't do any other sport in HS. She played soccer prior (go figure, most good runners do).