In reply to weirdfish:
Based on 10k on road which is a reasonably standard distance:
For a male runner no age adjustment
sub 60mins - entry level, just above jogging
sub 50mins - average runner
sub 40mins - reasonably keen runner
sub 36mins - decent club level approaching top 10 in many races
30-35mins - serious, would be winning things
sub 30 - top level of amateur
Probably far too basic but hopefully a pointer