I'd actually say that what happened to Aldo is a bit different from what happened to Silva. While yes, the mystique is gone for Silva, he's also just old and he sustained a leg injury that should have ended his career on the spot. The 38-year-old losing to a stronger 29-year-old with the skillset to neutralize him is what should've happened with Silva and Weidman. Add in the injury, and shyt like his ostensibly losing to guys like Derek Brunson isn't suprising.
I think you're right about Aldo, though. Here's a guy who, at 30, should still be in the prime of his fighting life and dominating his division. Instead, he looks human when matched up with top level guys, is abandoning strategies that carried him throughout his early career (where were the leg kicks?), and generally seems like time is starting to pass him by. It's not like he sucks now or anything, but whereas Silva's decline can be attributed to age+injury, Aldo's seems to be a product of him deciding to fight completely differently at some point post-UFC and everyone realizing that he's just a man after getting embarrassed by McGregor.
I dunno, I just don't think you can really compare the two that easily.