Average ratings are based on the published values and not the values entered in your own log entries.
I did this on a Friday afternoon when nobody was around except the workers at the nature center. I hiked all three loops starting in the north end of the park, down into the nature trail and farm trail section then back to the north parking lot.
That length is a guess based on the maps. I don't have a good time estimate because I was Geocaching at the time as well so that throws time to the dogs.
Went birding with the mother-in-law. Saw tons of birds including the woodpecker she was after.