This is a simple example, for compare number and scale damage, hoping the future Shred don't pre-require positional.
CAT DPS Gear - Self Buffed - 3710 AP
Test on Elemental Air lv. 69 in Shadowmoon
Rend and Tear 4/5 point ---->Improved damage in bleed for 16%
Type of SR Damage RATIO
Normal Crit 1539 100%
Bleed Crit 1763 114,55%
Mangle Crit 2043 132,75%
M + Bl Crit 2319 150,68%
Tryed Maul Too:
BEAR DPS Gear - Self Buffed - 3080 AP
Maul Normal Average Damage: 540 RATIO
Maul Crit Average Damage: 1050 100%
Maul Crit BLEED (Lace) Average Damage: 1520 145%
Maul Crit MANGLE Average Damage: 1715 163%
Maul Crit BLEED (Lace)+ MANGLE Average Damage: 2260 215%
Strange number for Maul, but the damage is fine now in Dire Bear.
Don't try Enraged, Mob slayed in 3 swing