Rankings are determined by how well you do in the tournament. MyBrute publish the rankings here: [1].

Rankings in order from highest to lowest:

Icons Ranks Hour
Lvl 0 Brutal Legend 21h Finals
Lvl 1 Dentist of Chaos 20h Semifinals
Lvl 2 Satan's Biceps 19h Quarter-finals
Lvl 3 Sword Swallower 18h Final 8
Lvl 4 Hemoglobin 17h Final 16
Lvl 5 Beserk Soul 16h Final 32
Lvl 6 Vengeful Flame 15h Final 64
Lvl 7 Iron Fist 14h Final 128
Lvl 8 Richter Thumper 13h Final 256
Lvl 9 Sticking Plaster Ripper 12h Final 512
Lvl 10 Desert Batterer 11h Final 1024
Lvl null Padawan 4h - 10h Starting out

For example, to get the title of Brutal Legend, you must at least reach the final of a tournament.