its 1.2% crit chance reduction for every 100 resil, considering most people stack ICC off set, jewels and weapons, they should be around 950 to 1100 resil, the crits you get from improved ambush, malice + gear is enough to crit at least 7 out of 10 ambushes in pvp
4k ambush is a good chunck of damage, even 3k is good enough, you get at least 3 ambushes from a shadowdance opener plus a small window to react or pull a 4th one
i dont know which version of rogue you are familiar with
in wotlk armor is relevant, you gotta be patient and rotate your CCs DR, looking for opportunities to restealth or vanish > sap wait for DRs > open > CC > restealth, and keeping doing this, avoinding taking damage while shadowdance is on cooldown, you lack any energy regain so you rely on restealth to get some energy back, this is sub 101 basically, doing damage while they cant hit you back, everytime you re-open on them you do some substantial damage, this is something assassination rogues cant really do because they rely on deadly poison stacks that requires them to stick to the target and burning defensive cooldowns much earlier, while being unable to gouge and blind frequently on the target
you can take the newbies full combo path like
cheap shot > hemo > backstab to 5cp > kidney > backstab running out of energy, never having a chance to shadowdance properly
then improve it by mixing gouges
(with 3/3 initiative) cheap shot > hemo > gouge to 5cp and bait a trinket > as gouge expires full kidney to pressure a trinket > as kidney expires you can get another gouge or blind and restealth and keep pressuring, whenever they trinket you blind, restealth and open with full shadowdance
this is the very basic playstyle you want to focus as sub, most people know how to deal with this, so you must be ready to disarm, evasion, cloak, whatever is needed to survive their first reaction and take control
you can however play like this with 41/5/25 prep/muti and combat
but in 3.3.5 41/5/25 loses to sub in both damage and mobility, and combat is better if played KS AR normaly and you cant spec prep as combat
you want to avoid doing zergs with your team in BGs and do your own thing alone, unless they are fighting for an objective that is your priority aswell, taking whatever you can by yourself and fighting isolated people, you dont rely on healers that much and with 2 vanishes you can stay safe from being zerged, other classes cant do this so let them do the zerg, its very hard to 1v1 a rogue defending objectives, it forces more people to go after you, weakening the enemy group fight