I think the financial crisis was a pretty big thing and Obama handled it about as poorly as humanly possible. It set the stage for everything getting much worse.
People in general had a very high expectation of him. The right expected him to fail because he's black, the left expected him to be better than white democratic presidents because he was black. He was just a well meaning decent human being trying to lead a country. there are worse and better presidents for sure. But he wasn't the disruptive and young new leader people hoped for.
There are many, MANY ways things could have gone dramatically worse. There are things that could have been done better, but "as poorly as humanly possible" is a trivially wrong statement.
Here's one way he could have handed it dramatically worse with a huge amount of empirical evidence: started lobbing random tariffs and abandoning trade deals and going isolationist.
