Doesn't seem like you're going to get an answer so I'll provide some links. This thread and this post should both suit your purposes. Especially these two parts:

The Empire wasn't a streamlined, central bureaucracy - it was a sprawling multi-ethnic empire, stretching from the Balkans to Yemen and from the border with Persia (modern day Iran) to Egypt (until Napoleon). In order to accommodate the incredible diversity within Ottoman territory, the Ottoman government relied largely upon local elites to govern for them. It's hard to generalize here without making this lengthy post lengthier, but basically, as long as taxes were paid and there was no open rebellion, the sultanate allowed locals a significant degree of autonomy, especially for the time.

and

Throughout the centuries, the Ottoman Empire began to decline in economic terms compared to Europe and its more efficient capitalist system. In order to reverse this trend, Ottoman sultans attempted to open up the Turkish economy for European investors. Many deals, known as the Capitulations, were made with European nations that allowed European merchants to move more freely within the Ottoman Empire. Examples of certain Capitulations includes European citizens not being help to laws in the empire ( which operated mostly under Sharia law) and paying very few taxes.

Mansfield concluded that through economic means Europe was able to peacefully infiltrate into an empire that they saw as hostile and slowly weaken it. Europe was able to further outpace the empire because of the one-sided trade environment that was created. It also didn't help that many European merchants abused the Capitulations by breaking laws or avoiding the minuscule tax all together. By the 1900's, the Ottoman Empire was only able to continue to exist because of European nations propping it up. The empire was able to last until the end of the First World War because European powers feared its collapse would cause a power vacuum which would lead to a sort of European civil war.

Basically, from my secondary knowledge about the subject and as explained above, they just kind of declined. There was no real drama about it; it was a slow and arduous decline (or rather slowing down) in the face of rapid European economic rise and dominance. Combine a highly decentralized poly-national empire, a slowing population growth, little military experience comparatively globally or on the European stage to hone their doctrine/experience, imperialist aggression slowly beating them back, and economic dominance from Europe (both in a pure capitalist sense and in an 'economic aggression' sense) and the empire just kind of...declined.