(Apologies in advance for a long post!)
In terms of results, all I can say is that this is easily one of my most consistent decks for me, and I rarely ever lose. My friend ThermalStone plays most of my better decks regularly in ranked, and he's had the same experience. Collectively, we've played about 50 games with the Ogre deck, and lost only about 5. 2bestest also reported great results with his modified version.
It's similar to my
Seance deck in that I have 9 out of 10 runs with it all the time, as does my friend, yet Barney went 0-4 with it when he tried it. I can't explain why without seeing either of your games, but just give my experiences with the deck (and those of Thermal's that he relates) which are nothing but solid. That said, I can look at the opening hand you did report.
You say you had a
Goblin Arsonist,
Viscera Dragger and
Ground Assault. I'll assume you had at least two lands in your opening hand, and therefore you have at least two other, unidentified cards. You say you then drew two lands and a
Nemesis of Mortals, and the Goblin died, so your first four turns should have gone like this;
T1: Land,
Goblin Arsonist - 5/6 cards in hand, depending on who went first.
T2: Land, Cycle
Viscera Dragger and draw a card with it. Block with the Goblin, who dies in combat (should get a kill). 5/6 cards remaining.
T3: Tapland,
Ground Assault to clear the path for the upcoming Nemesis. 4/5 cards remaining.
T4: Land,
Nemesis of Mortals. 3/4 cards remaining.
You now have a 5/5 on T4. Two dead enemy creatures (what's surviving a T2 Arsonist and a T3 Assault? Not much) a 3/3 Unearther in the graveyard and 3 or 4 cards left in hand. If even one is a land, you're able to start casting power cards on T5.
I genuinely can't see how that sample hand is bad unless you misplayed it, or they got god draws. That's a great opening by anyone's standards, both offensively and defensively.
You say you don't feel comfortable on the offensive here, but the deck isn't really an aggro deck anyway. It's a deck that stops the opponent over-extending with wipes and retalatory attacks, or defends with Spiders and chumps, then wins by KO attacks. Either mass Spiders/Sparolings (with or without haste), post-wipe Unearth attacks, unblocked Wrecking Ogre targets, or high power Prowess tramplers. Ogre Spiders may not be a consistent win-con for you, but it isn't meant to be the focus of the deck. It's just one (good) finisher among a variety of other win-cons. I called it an Ogre deck because the Ogre Battledriver and the Wrecking Ogre have won me an equal amount of games, and the Viscera Draggers (who are Ogres too) are an important engine (along with the Wayfinders). There's much more to the deck than the Battledriver.
Regarding Draggers though, why would I remove the Draggers for
Phyrexian Ragers? I've already gone on long enough, so won't go in-depth here, but could write a lot of mechanical reasons on why the Ragers are a poor substitute for the Draggers. Mechanically they seem similar, but they're as different as
Elvish Pioneer and
Satyr Wayfinder in my book - another couple of cards people sometimes equate, wrongly IMO.
Lastly, regarding Rabblemaster being
Shock fodder - that doesn't really matter. The fact it dies to removal is no reason not to include it. It's the old
Doom Blade argument. Everything dies to removal, and Shock is easily the Doom Blade of D15. At least this one has the potential of generating Goblins first that have later uses in the deck (
Mycoloth,
Hunters Prowess/
Wrecking Ogre platforms) and unlike most decks that use the Rabblemaster, It's not the core card in the deck, and nothing else you care about is vulnerable to Shock either.