Offensive dispel and spell penetration

Hello,

recently I did some googling on how exactly does dispelling work in regards to your and your opponent's stats and I am seeking confirmation on that from whoever does some PvP and did their research as well :)

I found out that following factors play a role:
* Hit rating
- you need that 6% (4 is standard cap, 2 for racials) hit rating to not miss your own cast
* Spell Penetration
- your dispell can be resisted if the target has resistances to your dispel's magic school
- for me as a mage, Spellsteal is arcane, so arcane resistance might negate it if I don't have penetration
* "dispel resistance"
- those are the talent such as Arcane Subtlety (mage) that give a change that your dispels will fail
- there is nothing you can do to negate this

Now, this all sounds nice and easy on paper, however my friend plays a priest, we aren't really geared yet (missing spell pen) but what we are seeing are excessive failures to dispel targets in PvP.
His Dispel Magic should be a Holy spell according to some WoW databases I browsed and there is no such thing as Holy resistance in game - does that mean he doesn't need spell penetration for his dispel calculation?
I see people (for instance shamans, whose dispel is Nature to which you do have resistances) can dispel me as a mage fairly easily even thought I use Magic Absorption talent and Mage Armor with Arcane Shielding talent which amount to 140 all resistance on self buff which surpasses even the pen most people play and makes me all the more puzzled. And I OFC run dispel resistance talent as well.

Anyone has any experience with this?

there isn't much to add, you said almost everything.

Just about "Hit rating", your enemy might have a talent which reduce chance to be hitted by magic spell. Like:
http://wotlk.cavernoftime.com/spell=31872 "Reduces your chance to be hit by spells and ranged attacks by 4%..."
http://wotlk.cavernoftime.com/spell=30895 "...reduces the chance you are hit by spells and ranged attacks by 4%..."


Yes, "Dispel Magic" from Priest is Holy school and there is no "Holy resistance" but it can still fail due to resistance granted by enemy's talent (30% resist chance)
Maybe your priest is using rank 1 Dispel magic? (instead of Rank 2 )

Also, Hpala has a talent that when procs, add an additional 30% resist protection: http://wotlk.cavernoftime.com/spell=53553 (you will see "miss" if you fail to hit your enemy because of this proc)

I guess your are not playing on Blackrock realm but you can use it as test realm. (instant lvl 80 and free gear)
So you can test by your own dispel mechanism; like mage chance to resist to shaman purge etc... (on combat log you can check when you resist to a dispel effect)

So what hit rating (for spells) should one aim for?` Since with the talents you mentioned, that would effectively mean up to 10% to cover up for basic, these talents and racial from BE.

Oh, didn't realize there is Sacred Cleansing as well. That's good to know.

And to answer you, no priest is using max rank of dispel.