Your heroic strike hit more than any other attack on sindra 25 normal.... are you sure you aren't delaying BT/WW through rage starvation?
Your slam! usage also seems abysmally low.
To put it simply, your WW is too low and so are your slam!s. Boorman easily doubled yours (hits for WW/Slam!) for that fight, and did 3K more damage. Either you got unlucky with frost tombs, or need to practice your rotation.