it all depends on what is considered great here are some criteria i use.
1. make the all time top 100 performers list, in the marrathon it is currently at 2:07.35
2. make top 10 in the world in your event by track and field news or some other legitimate ranking system.
3. win 2 or more major races, for the marathon it could be NYC, boston, london, dubai, rotterdam etc. i put down 2 as doing it one time could be a fluke, do it twice or preferably more it is legit.
4. placing top 3 in olympics or world champs.
some would say my standards are too low and have for criteria
1. a world record
2. being ranked #1 in the world
3. winning a certain # of top notch races
and some will say my definition of great is too high and they can lower the term great as low as they personally want.
with louie luchini i cant see him being great, but i could see him being a 2:11-2:14 runner.