The nation's economy is both sensitive and massive, meaning that small changes may not become apparent until much later. Also, Congress has much more power over the economy than the President.

Now, I'm a liberal who fully believes the economic disaster was brought on by unsound monetary policy (under both Democratic and Republican presidents) that gave banks far too much leeway in how they conducted their business, and I think the reaction by the Obama administration to the crisis was largely sound. But I know enough about the economy to know that it never is as simple as "it was good then and is bad now."