Answer:
from what i understand it starts talking about the death at line 2.
Explanation:
2. smart lad, to slip betimes away from fields where glory does not stay
-- i believe ita saying the athletes final rest, when they fall asleep ans go to heaven where glory doesnt follow, the field being a treasure hidden in a field based on matthew 13:44
3. eyes shady night has shut cannot see the cord cut
-- i think this one directly talks about the injury itself.
5. runners whom renown outran and the name died before the man
--i believe this is discussing the career was cut short, possible due to a fatal injury or health problem. they could not yet get their name well known before having to quit, and eventually pass on.
hope this helps