I should back up for a second, and clarify that the numbers I was going by weren't accounting for whether attacks hit or missed - henced why I usually mentioned accuracy seperately. You claimed that the thief was doing 20 damage with his At-Will powers, so I took a look at what damage other classes did with At-Will (and Encounter, etc) powers.
You are correct about the ranger - I think I was accounting for both Greatbow and Weapon Focus. That said, I think it is definitely worth noting that while rangers start a few points behind, they ramp up quickly, since every static bonus to damage gets doubled. I'd say they catch up pretty quick - and, yes, definitely burst higher when using encounters and dailies.
With At Will powers, they don't ramp up to similar damage until late Heroic or early Paragon.
Overall damage, they ramp up around level 7 when they get their 3rd Encounter power.
I'm also not entirely sold on the numbers you are using - assuming thieves will have combat advantage is reasonable enough, but assuming others will never have it is less so.
This statement is true for melee types, not true for ranged types. It usually takes quite a few levels before ranged PCs can start acquiring CA because the main two ways to get it are via powers/feats, or by shooting at point blank range.
Additionally, the attack bonus of your thief seems higher than it should be - and intentionally ignoring the stronger ranger encounter powers seems an easy way to dismiss the damage they can deal.
Ah, but you cannot have it both ways. You cannot ignore DPR with one breath ("clarify that the numbers I was going by weren't accounting for whether attacks hit or missed ") and then say "but Rangers get Encounter powers" with the next.
Either one takes into account all factors, or one filters it down to one specific area (like At Will attacks). Picking and chosing doesn't work.
So yes, when one considers the Encounter powers, Rangers do boost up their overall Encounter DPR more than when Thieves take into account Backstab. But that extra damage still doesn't catch up to the Thief until 7th level. At 3rd level, the Thief still averages more damage per encounter.
And Daily powers are hardly noticable at heroic. A single Daily power that does 30 damage actually increases DPR for the day per round by ~1 (i.e. 5 encounters, 6 rounds per encounter). Yes, it is part of the overall damage picture, but Weapon Focus adds more DPR per day than a Daily power.
A ranger isn't going to use a random 2W encounter power to deal damage - they will use something like Two-Fanged Strike, potentially deal 2d12+1d6+Dex+Dex+Wis. Dailies include options like Skirmishing Stance - potentially +1d8 damage every round for an encounter. Or Guardian Arrow, which can basicaly given an extra attack each round against one enemy.
Skirmishing Stance is again, ~30 points of damage (4.5*6=27).
Guardian Arrow could be a lot more damage, especially against a solo, but if it is against an elite or a standard, it actually will often result in ~30 damage (or less) since the foe will go down before the entire encounter's number of rounds has passed.
And really optimized builds can even bypass the thief. A dwarven ranger with a gouge is looking at ~17.8 average damage via Twin Strike. Or ~25 average damage on the round he uses Two-Fanged Strike. Now, he's more fragile than the rogue, and not as simple to build - but definitely leaves him behind in terms of raw damage.
This is both illegal and mathematically incorrect.
First off, last I looked, a gouge is not a double weapon. It cannot be used with Twin Strike.
Even if it could, the Ranger still cannot really catch up to the Thief. Ranger 20 Str. Rogue 20 Dex. AC 15 same level foe. We'll give the Ranger Wis 14 which is the maximum he can have with a 20 Str Dwarf.
Rogue: 1D6 Shortsword, +2 Weapon Finesse, 2D8 Sneak Attack Backstabber
Ranger: 2D6 Brutal 1 Gouge, Twin Strike
I'll give Rogue CA every time since it is a class feature. I'll calculate damage for the Ranger with and without CA.
Rogue: 16.075 DPR
Rogue with Backstab (+3 to hit) once per encounter: 22.45 DPR
Ranger: 13.87125 DPR
Ranger with Two-Fanged Strike once per encounter: 21.21625 DPR
Ranger w/ CA: 15.68125
Ranger w/ CA with Two-Fanged Strike once per encounter: 24.30625
The CA every time Rogue beats the no CA Ranger in a 6 round encounter 102.825 overall damage to 90.5725.
The CA every time Rogue slightly beats the no CA Ranger in a 6 round encounter 102.825 overall damage to 102.7125.
So yes, if the Ranger has CA every single time like the Thief does (and he could use a gouge), then the Ranger will approximately tie him. But, the Thief can count on CA more often than the Ranger because the Thief can get CA from one of two stances, from flank, from allies, and from First Strike. The Ranger can only get it from allies or flank.
The Thief has an AC of 17. The Ranger has an AC of 13.
Sorry, but this melee Ranger will not even be conscious all 6 rounds to even try to tie the Thief in damage.
If the Dwarven Ranger lowers his Str to 18 and/or his Wis some, he could get +3 more AC (max AC 16 at first level). But then his encounter DPR drops by 6 in both the no CA and the all CA cases.
Note: The Scout doesn't do as much damage as the Thief either. The reason is that he does not get Twin Strike. He gets Dual Weapon Attack which requires that the first attack hit in order to get the second attack. +2 damage for Spinning Axe Mastery doesn't add enough to make up for the one round in three getting one attack instead of two.
I'm not seeing it. You picked an illegal 8 average damage weapon (which would be unheard of damage for a single handed weapon) and still didn't quite catch up.
If you limit yourselves to average 1st level characters, yes, the thief probably comes out ahead of the rogue. Though I don't believe by as much as you are claiming.
Once you get a few levels in, the ranger has pretty much caught up. Each new bonus to damage helps out more. Each new encounter and daily power is significantly stronger than each new backstab the rogue gets.
And, as noted, many other strikers are comparable. You focused heavily here on the ranger, but ignored the fact that many other strikers deal similar damage as well.
I only focused on the Ranger because that was your suggestion as someone who could do average 20 points of damage in a round with Twin Strike.
He doesn't average 20 damage at first level, regardless of how you build him. To get to 20 damage, he needs to hit twice, get 3.5 damage for Hunter's Quarry, then average 8+ damage with the other two attacks. What one handed weapon averages 8 points of damage? Typically, we are talking 5.5 points of damage (longword with weapon focus, or bastard sword). It's tough picking up that extra 5 points of damage because the game doesn't have weapons or feats that add that much.
He can manage 20 points in a round with either criticals or good rolls, but he cannot average it.
Also, I've already posted the math above as to why it takes the Ranger level 7 before he catches up in Encounter damage (due to his Encounter powers). And he doesn't do it with Standard Action Encounter powers that do more damage. He does it with Immediate Interrupt or Reaction Encounter powers that give him more attacks per encounter.
