I went to college in the Northeast and had a pr of 26:42. Then moved to CA and ran a couple open races and ran 26:28 and 26:36. Thing is that I was in much better shape in college. I think I might have broken 26 if I was at my college fitness for those races. Woulda coulda shoulda...I know. My point though, what is an average course? What is a fast course? The courses I raced on in CA were on much easier surfaces (really short grass, hard packed dirt, and even some concrete as opposed to mud and long grass).
The other thing, how do we define decent? Is anyone who qualifies for nationals at least decent, or is it top 50 at nationals? How about top half of a D1 race? Or just top 7 at their school? When we say decent, everyone has a different picture in their mind. To go further, the range between good and bad d1 programs is absolutely huge. I raced against plenty of teams that I would have been the number 1 runner and against plenty of teams I would have been cut from. What someone considers decent is probably more about who they run with everyday and the level of competition they generally face more than any type of national standard.
I would say that unless a person is overly self-conscious and cares what people on this board have to say (this person obviously does...hence the post) he or she can consider him or herself to be at least decent if he or she is consistently improving and getting to the next level. At least in that case the person can't define his or her limits. Once a person gets content with their ability, they generally start to suck.