10% discipline gap with Prussia, as well as a 20% gap with the rest of Europe. For a supposed mass of unwashed Muslim peasants, that's an awfully high discipline (I suppose that could apply to anybody with a highly disciplined, large army, but even more so when that army is 300 thousand strong.)
The Ottomans were hardly unwashed muslim peasants. Have you read of the Janissaries at all?
And sure, Prussia can field two or three 40k armies, and have fantastic leaders on all of them, but does that really matter when they're up against armies three times their size?
Yes, it does matter. Or did you completely forget about the bitching and moaning about Prussia a few months back?
Nobody else has national ideas that triple their manpower. People say that Russia have OP manpower ideas - Ottomans have the capability to triple their manpower almost all the time. As well as that, pretty much all of the other Ottoman ideas are really good.
Almost? Ghazi only triples manpower in war against heathens, it does not work (IIRC) against Heretics, and it does absolutly nothing in peacetime. Russia, meanwhile, gets NIs that double its manpower 24/7, on top of having better overall NIs.
Infact, take away Ghazi and Russia's manpower, and what do both sides get?
Russia: -10% Tech cost, -50% Infantry cost, +50% Land Force Limits, +0.5 Army Tradition, +1 Colonist, +10% Production Efficiency, -15% Core Creation Cost
Ottomans: +10% Discipline, -33% Core Creation Cost, +33% Religious Unity, +3 Heathen Tolerance, +15% Cavalry Combat Ability, -10% War Exhaustion Cost Reduction, +10% Tax Modifier, +10% Trade Income modifier, -10% Ship costs
The Core Creation Cost, Religious Unity, and Ghazi literally have to carry the Ottoman NI set, while Muscovy gets all-round amazing bonuses.
I'm not complaining about Ottoman's power in Singleplayer, mind, just that in the hands of a player in a MP game, they can completely dominate, regardless of what other people do (short of stomping them right at the start).
If Ottomans are dominating, theres probably a reason for it. Austria for example dominating the HRE is a really bad thing for Europe because Austria has abysmal land armies. Of course, the only real problem is that the Janissaries decadence events may not be triggering properly/reliably, and its the Janissaries that give the Ottomans a huge amount of its early game strength.