i've got the same question: why bash over frenzy?!
i used to play with bash few days ago, cuz bash do more dmg (24% versus 20%), BUT frenzy is way more faster to refresh your buff, and for you to monitoring it (buff below your skilltab)
and btw, can you kill goblins with bash @ mp10, alone? i cant - with frenzy, i can

and, finally, frenzy does NOT apply ASI bonus to sprint and ww, as ftang posted above.