I think it comes down to gear. I really didn't spend a whole lot on mine, and not all elites can be stun locked that well. Act 1 elites of course go down very quick. Act 2,3 take a bit more time and possible kiting. But the stuns really help reduce damage and the procs like the arcane laser.

I tried 200% MF on my guys, and it seems like it makes so little difference. Before, I did act 1 to butcher and had a bag full of rares. Now, I get the same thing, even though my MF is up by 150%. Very strange... Maybe I was killing so much faster I did more packs or something. Either that or you need like 300%+ MF

I also noticed that I get feared a LOT more and get knocked back a lot more. Also, I'm getting these weird packs that are sometime stacked on top of each other. Or the yellow guy will have totally different affixes than his minions. I'm not sure if this was a recent change, or if it's because in MF gear I kill things a lot slower and I'm starting to notice.