SOS: Rogue Help an' I Give Up

I've got a rogue friend -- okay, I've got many friends, but this particular one is the one with a problem. He came to me about it... which is unfortunate because he's a rogue. And rogues are completely foreign to me: closest I get to a rogue is my druid, who is more bear than anything. Say something in rogue-speak, and I'll stare at you baffled unless you can give me a druid equivalent. Then I'll stare at you and say, "I don't know, I'm a big stupid bear or a tree".

Anyway, his problem.

It's his DPS.

He reads Elitist Jerks, is combat, and is in a mix of heroic and normal instance gear, with a few crafted here and there.

Recount says his abilities used are [this is through all of... Old Kingdom, heroic]:

And this is what Armory says about his stats.

His DPS is at 1.3K, and he's completely baffled as to why his DPS isn't higher / as to what to do to increase it.

As I know nothing about rogues, I'm turning to you guys for help. It is a gear issue, or is there something that he's doing wrong? If it's the latter, pray tell, what and how to remedy it.

Oh, and as a side note, being very last on activity meters in a twenty-four man raid [being 532 to the top activity meter of 1131], but being eleventh on overall damage done and second on DPS [2,669DPS vs. my 2,629DPS -- only five of us are about 2.1K -- everyone else is below 2K] makes me very very sad. Five or so attempts on Noth this data was collected. I know Mel loves her aggro, but when the tank uses Shield Slam six times from engaging Noth to him being at 48%, through two teleports, it's hard NOT to pull aggro. Activity was so low because I'm either standing around managing cooldowns [popping Mirror Images, Water Elemental, Icy Veins], Invisibility-ing and letting it go all the way, standing in Ice Block for the full duration, or decursing. Or twiddling my fingers because if I hit Noth again, I'll be tanking him for a few seconds. If I'm not that, I'm dead.

It's very disheartening, and I think, for my own sanity, I'm going to not attend that raid anymore. I want to help, but at this point I'm in Naxx on both normal and heroic on all three of my characters, and if I'm going to be going in there so much [yes, I'm crazy and have no life, I know, it's a transitory stage of my life], I really don't want to spend even one raid wiping excessively -- if I'm in there a lot and it's vaguely successful [such as we can down at least three wings in three to four hours], that's fine. We're in, we kill stuff, we die a bit, we're out.

But to go in and die over and over again to a boss... I don't think I have that much patience. Especially if I only have an hour's break between that raid and my Naxx10 run on the same character.

I hate to leave a group, but... somehow, I get the feeling that my reasoning is justifiable. Now if I can keep my newly built bond with that raid leader...

Mind you, I like the people in the raid. And I will understand if they forever will call me bad names for leaving after wiping and getting nowhere, but I just can't do it. Not when I have so many other raids I attend.

Not when I feel like I need heavy therapy afterwords in the form of a few hours of blog reading or reading in general.

... Yet, why do I feel so bad?