drop top and bottom values before computing average

Attached is a sample spreadsheet which is used to computer team averages in a dart tournament. There are two different games played, and each has it's own stats at the end of a match. After teams have played 2 matches we look at their stats to determine if they're shooting above their stated ability. If they are, we re-rate the team.
In the past we used all their stats for the games played. at our next tournament I'm being asked to exclude the top 10% and the bottom 20%. I have not been able to figure out how to do this. To make things more difficult, the stats for the two different games are totally different from each other, but the scores to be excluded could come from either set.
In my sample F7 computes the average for their "01 games" (data is in row 7 starting with P), and H7 computes the average for their "cricket" games (data is located in row 8 starting with P).

Any suggestions?

Let me know if I need to explain anything (or everything) better.