An interesting comparision . . . .maybe . . . is with a high school senior here in Waco named LeJerald Betters (who, by the way, is going to Baylor next year).
Betters was the 5A state champ in Texas last year in the 400 (46.42) and the triple jump.
This year, Betters has run 20.81 for 200 meters, 47.02 for 400 meters, and 1:57.37 for 800 meters.
He has also gone 48-2 in the triple jump. Quite an athlete!
http://www.wacotrib.com/sports/content/shared/sports/preps/tx/waco/spring/boys_track/4a_track.html#D11A
Granted, Betters is in high school and thus lacks the strength of someone Wariner's age.
But this set of performances shows that a true 200/400 sprinter has a lot of difficulty running a decent 800. The kind of sprinter that Wariner is and Michael Johnson was is a totally different creature than a 400/800 guy like Juantereno (who was an anomoly).
By the way, LeJerald Betters ran that 800 on a lark at the regional qualifiers meet (I believe it was the first he had ever run) just to try to get the school record. He went out fast and died the big death over the last 400. And he failed to get the record.
For stat freaks, here's the link to Central Texas' all-time track and field performances:
http://www.wacotrib.com/sports/content/shared/sports/preps/tx/waco/spring/boys_track/track_bests.html#D11A