RANKX returning variable, TOP 1, 2, 3, 4

So, each account manager has a different best selling, second best, third best MRK. 

My visualization was built to show 4 graphs that will return the same information (Coverage), for the first, second, third, and fourth best-selling MRK. 

How can I show only information from the best selling in the first graph, 2, 3 and so?

 I'm trying to filter with the rankx selecting 1 and isn't working:

rank_mrk = RANKX(ALLSELECTED(tab_mrk[MRK]),[sum_rank],, DESC, Dense)