So I think I have done what you are looking for but I came at it from a different angle. My version only uses table calculations for the ranking. Removing the table calculations from the current month and this month last year calculations makes things much easier to work with. Take a look at the Date Selection Check tab to see more on what I am doing. The calculation I used are set to automatically find and use the most recent month in the data set. You would need to adjust the calculation if you were to load partial months going forward so you don't end up comparing 1-15th this month to 1-31st of last year same month.
Top 25 growth accounts V2.twbx 15.1 MB
Thank you so much! This was a huge help.
Glad it worked for you!