Sporadic values for dates, want to see last score until next score is submitted

Sam,

Consider setting up your score calculation so that it includes the ALL() function for the date.  Your score calculation might look something like this:  AVG(score,ALL(Dates)).  This tells the calculation to ignore the date filter.  Note:  You have to account for each grain of Date, so if users can filter on years, quarters, weeks, days.  Your calculation will have to add an ALL for each.  Something like: 

AVG(score, ALL(Years in Dates), ALL(Quarters in Dates), ALL(Months in Dates), ALL(Weeks in Dates), ALL(Days in Dates))

Hope this addresses your use case, Jim