You are right that Avenging Crusader is not affected by Mastery.
So, I’ve seen a number of people scratching their heads when it comes to not stacking crit. But… I don’t really understand why you would necessarily stack crit - maybe it had more value in the past?
You get more infusion of light procs… but the value of crit is already depressed some because of the 30% base crit chance on Holy Shock (any spell/effect that gives a base crit increase reduces the value of that stat from gear). If you add 1000 crit to your gear… that’s like 6 more infusion of light procs in a 5 minute fight if you are using the build that can cast the most Holy Shock possible (which most people don’t even use). That just doesn’t seem overwhelmingly compelling to me - to the point that it would be an obvious choice.
That being said, we are in the process of re-calculating holy paladin stat weights. I adjusted the rotation to make more efficient use of Infusion of Light procs - and I think the result will generally be that crit gets a bit more weight than it is right now, which I think will make folks more comfortable. It is interesting that even wasting a couple procs or not getting full healing from them is enough to make crit weaker, though. I wonder if people are really accounting for this when they play?
I am going to add in more robust raid positioning for the healing scripts, but even still, Holy Paladins are often up in melee, mainly healing melee players, so I think the value for mastery that we have is pretty realistic.
Another reason why crit for healers will, in general, get valued a bit less by AMR across all specs is because we account for sources of effective healing that spreadsheets and napkin math don’t really have a way to deal with. Like: damage reduction from Versatility, damage mitigated by BoP, Divine Shield, etc. Those aren’t big… but all added together you end up with a percentage of your effective healing accounted for by effects that cannot crit. This is also why Versatility is ranked so highly by AMR - we actually are able to give realistic value to the damage reduction portion of the stat - that’s free healing!
When it comes down to it, though… the difference in potential healing throughput with the different stats for healers is just not that drastic. There isn’t a huge swing. If you want to stack crit, you’ll be fine. We offer one solution that definitely works - and we know it works because we test it with our robust healing simulator and use our advanced gear-ranking methods to analyze those results.