+33% FL from NI is no joke. The Ottos commonly pick quantity and offensive as well, which is another +50% FL & +20% FL. Couple that with them usually being one of the AI nations with the most dev and it is no wonder that they can field the largest armies, even rivaling Russia when it comes to troop count.
Fortunately the Russian AI is improved in 1.30 and they now know how to build artillery. But still their huge territory weakens them. I believe that the Russia x Ottomans match up in the hands of the AI has more to do with the Russian AI inability to deal with its vast stretches of land rather than the two countries raw power.
The Ottos have been having trouble expanding into the Levant since CoC. Technically that is their best expansion route (right religion, right culture and rich provinces) but the Mam are very strong early on, so the Otto start expanding everywhere else following their perma claims until they are strong enough to take down the Mam. What kills the Ottos in 1.30 is the merc change -- they simply cannot deal with it and that cripples their early game expansion. They have always relied quite heavily on mercing up to expand as opposed to the Mam that always hoard manpower (because they rarely start wars).
When EU4 was released, the Ottomans had far and above the best and most complete missions. How far have they fallen! I honestly wish that their missions would be revised.
They are supposed to explode when the late game rolls around, but there are two things that kind of make this impossible: Cradle of Civilization and Rights of Man. If you play with both of this DLCs disabled, the Ottomans will invariably die come the late game when they get a bad ruler, as they should (or at least have trouble continuing expanding). CoC made it too hard for the AI to trigger the Janissary coup as they need many, many janissaries; the pashas make their empire too stable basically for free. Rights of Man guarantees that they will have at least good monarchs with their unique government type, which is a huge issue when their unique disaster calls for them having a poor monarch.
The balance in the middle east is all sorts of wrong. Ottomans barely expand into the Levant, Mam and the de facto power there, Persia never forms, etc.