you are comparing apples to oranges.
these guys aren't even in the same camp.
gregson is clearly more talented than centro. ryan gregson is a lean beast and is a very undeveloped HS runner, as lukezic was, but with much faster natural speed - 48 point in the open 400 is incredible. centro was a good high school runner, but he doesn't belong in the same camp as webb, ritzenhein, hall or someone like gregson.
at the national high school championships, gregson closed the last lap of the 1500 in 54.
"In November Gregson, who has just completed his HSC at Illawarra Sports High School, south of Sydney, set Australian under-18 records for 1500m (3min43.84sec), 3000m (8min01.34sec) and 5000m (14min14.35sec)."
http://www.theaustralian.news.com.au/story/0,25197,22914719-2722,00.html