Average cells based on data in adjacent cells.

This one is killing me. I know I'm close, but I can't figure out where to go from here. I'm breaking data down into progressivly smaller fields (time of day, day of week, etc.) using =SUMPRODUCT and I need to add something to average the affected cells excluding zeros and blank cells to it. The formula I'm using now is "=SUMPRODUCT((Detail!$W$2:$W$4019>TIME(5,59,0))*($W$2:$W$4019<TIME(10,0,))*($Z$2:$Z$4019="Monday")*($Q$2:$Q$4019="Y"))". Now I need to average the times listed in row "L" for all of the rows that formula is sorting out.
I hope that makes sense. I would attach a copy of my spreadsheet, but it's got some potentially sensative infromation in it that could get me fired.
I appreciate any ideas or suggestions.