No, i was thinking about a more conservative 18/16 human with expertise and weapon focus... there are several ways to get those numbers. But i really forgot to take backstab into account which lets the thief come slightly ahead of the slayer and maybe even the warlock.
But i will still imply 95% hit chance because this is when you should do your nova. A single hit of the cleric with righteous brand will increase an 80% hit chance to 95% which is a good indicator for when to start your nova...
While that's true, very few Leaders have At Will +3 bonuses to hit. For example, a Lazer Cleric only has +2.
And, the AC of most foes that a player wants to use a Nova against will tend to be higher than the AC 15 of a same level foe.
A heavily optimized to hit Slayer can get up to 95% for a Nova round if allies help, but that might be a bit more rare than you are assuming. Especially if the Slayer starts at Str 18 as per what you just wrote here.
Not all Slayers will have Poised Assault. Not all foes will be same level. Not all Leaders or allies will be able to help. The Slayer PC will not be able to wait until the Leader gives him a bonus, he'll be in situations where he has to Nova now (like when he has 10 hit points).
Your assumption of 95% chance to hit in a Nova round is overly generous. More like the exception than the rule.
The difference between the Thief and some other Strikers is that the Thief comes to the table with the super to hit bonuses already available to him (the Avenger is this way as well, as is the Warlock if he uses Gift to Avernus a lot).
The Thief often does not need another PC to give him flank or give him a power bonus to hit.
He can be the last man standing in a fight and still do awesome damage (this happened to me just last Sunday, all PCs unconscious, my PC with 6 hit points vs. a Dragon and his 2 remaining allies, I wasn't playing a Thief, but I did manage to win the fight).
The Rogue in a last man standing scenario is usually hurting. He can knock a foe down to get CA from prone and then use an AP to get Sneak Attack, or he can use a higher level special ability. But, the odds of him still having an AP or special ability at the end of a last man standing fight is probably pretty rare.
And, it's not just last man standing fights (which tend to be rare), but just fights where the Striker is off to the side in a fight on his own.
The Thief can bring +2 CA and +3 Backstab and +1 Weapon Talent (at level 2) to the table and not even need Heroic Effort like many other Human Strikers to mostly ensure that his Nova round works.
+6 already without help from a single PC ally. That's huge. Allies don't need to give them power bonuses to hit or combat advantage, allies can give them power bonuses to damage.
Boom!
A PC ally wasting an action doing Aid Another and giving the Thief flank? Why do that when the Thief doesn't need it and the PC ally can use his action for something more worthwhile?
If an ally is going to help the Thief, giving him a damage boost on a Nova round is a lot preferable to giving him a to hit boost. Silvery Arrow or Blessings of Wrath instead of Righteous Brand or Lance of Faith.
That's not necessarily true of most other Strikers.
All of those example i gave didn´t even really try to optimize heavily... if i take furious assault into account as an orc, heroic effort as a human or a good at will i can take with either half elf or human instead of heroic effort and soon you see those numbers start beeing comparable.
Yes. Comparable. For the Nova round. Not so much for the non-Nova rounds which make up a high percentage of rounds.
And just as a reminder: daze and prone are two conditions that may make a thief´s life hard and reduce his damage output considerably. Out of turn attacks from thief´s even if you theoretically can get sneak attack often don´t because the condition that allowed you to gain CA does not apply anymore if you did not get it by good old flanking.
This is something neglected in DPR. Not that you get out of turn attacks very often, but the possibility hinders enemies choices a lot...
Yes. Prone (which can be handled with an AP) and Daze are weaknesses of both the Thief and the Rogue. There are ways to handle them as well and they typically just lower damage for a single round in one encounter in X (most Thieves and Rogues are not dazed or knocked prone every single encounter, it's a bit more rare than that). Hardly worth mentioning in the big scheme of things (and either of these in round one for a Thief or a Rogue typically means little as they can walk around two weapon and throw a dagger at a foe who's init they have beaten).
As for Daze, have the Leader give the Thief a save out of turn (just like you are talking about the Cleric using Righteous Brand to set up a Nova round) and Daze becomes a lot less important staple of the DM's anti-Thief arsenal.
