Help with Formula

ragomes1972 

In my opinion, working with row numbers is a distraction created by normal spreadsheet practice; the underlying problem rarely depends on the placement of the data on the worksheet.  In this case, there is a more meaningful index 'sprints' to build upon.  You know how many there are and how many you wish to use; problem solved!

= AVERAGEIFS(Velocity, Sprints,">"&(COUNT(Sprints)-usedSprints))

 Using range operations to identify the required data can provide a sound basis for solution building but, in this case, they are derived from the 'sprints' counter and I think simply using the counter offers a more direct approach.