Hey Dreyda, I usually answer these sorts of questions over in the H90 thread, here:
So, to answer your question:
1: Frenzy’s stun via the Smite rune only works on the main target you’re attacking. So it’s pretty good when you’re finishing off an elite or killing the RG, but in density, much of your damage is coming via Bloodshed and AD, and because of the way the Bastion’s chain splits up your damage among many enemies, your dps is diminished for every enemy around you that isn’t stunned/frozen.
2: So, you’ve got 5.1% freeze on your belt. Unlike the stun from Smite, this can proc on every enemy hit by the Bastion’s chain. Let’s say you’re hitting about 7 times per second with Frenzy, and the chain just as frequently (this is not actually accurate, the animation on the chain is kind of weird, but let’s just assume this for now).
This means that you’ve got a 94.9% chance of not freezing each enemy on each hit. .949^7 = .693, so in each second of attacking, you have a 69.3% chance of not freezing, or a 30.7% chance of freezing each enemy.
3: Ultimately, what this will do, when compared to the higher freeze chance on AZ, is make freezing enemies more intermittent at first, but after about 10 seconds, about equal to AZ. This is because of the way mob CC resist grows for each second they are under hard CC, and decays for each second they are not under hard CC. In other words, freezing enemies a lot to begin with, using AZ, makes it harder to freeze them later.
Having only 5.1% freeze chance, however, does make it a little harder to time some things. One nice thing about AZ, if you’re fighting a big group of mobs, is that you can pop Wrath at your CoE damage element, spawn an Oculus circle, Charge into it, and in all likelihood, count on many of the enemies around that Oculus circle being quickly freeze-able via AZ. This adds another multiplier to your damage at precisely that time you have your other multipliers active (Wrath, CoE, Oculus), which is the most advantageous time to use it.
4: In conclusion, I’d say that the high freeze chance on AZ is definitely helpful. But, if your AZ is not well rolled and you are comparing to a primal Doombringer, you could certainly give Physical a try.