If this is anything like Classic and not changed at all, the following Ranks can be attained at following levels:
1-32 Rank 3
33-37 Rank 4
38-40 Rank 5
41-43 Rank 6
44-45 Rank 7
46-48 Rank 8
49-50 Rank 9
51-52 Rank 10
53-54 Rank 11
55-56 Rank 12
57-58 Rank 13
59-60 Rank 14
Keep in mind the cap of ...