The 4-piece bonus for T20 states that it increases the damage of Cobra Shot, Multi-Shot, and Kill Command by 15% during Bestial Wrath.

However, if you look at the buff it applies, Bestial Rage, you can see it's buffing Dire Frenzy by 15% as well (even though it's not in the tooltip):
https://ptr.wowhead.com/spell=246116/bestial-rage
(click "See more" under "Effect")

If this is intended to also apply to Dire Frenzy, it should #1 say in the tooltip and #2 also apply the 15% buff to Dire Beast, or else it makes Dire Frenzy the default choice with this set bonus. Another option would be to also buff Stomp and Chimaera Shot by 15% to make it consistent across the whole talent row. I noticed some big discrepancies testing different builds w/ T20 and think I tracked it down to this.

Just looking for consistency so we have talent choice!