I wont give you any of the math just personal observations.
I've tried an Alacrity build with as much power as i could get and about 5% alacrity and felt like I was swinging a rubber hose at mobs for all the damage i did. I dumped all the alacrity and as much crit as I've been able to get rid of for straight power/str and now it seems i can look at mobs and they die. More Powar