At the very least, it was on the ropes. And the first year or two of the Trump presidency—when he basically followed along with what the Republicans told him on most of the issues—was quite successful.
This is a great point, because the narrative from the Trump side is almost the exact opposite. That everything good came just from him, and everything bad came from the professional politicians. But the truth is kind of the opposite.
Trump's two most lasting positive impacts were court appointments, and the tax reform bill. Court appointments largely were outsourced to the Federalist Society for recommendations (Trump literally promised to have Supreme Court nominations come from a list supplied by the Federalist Society) and the Senate/McConnell. The tax bill was written in the House, and then rammed through by Ryan and McConnell. The kicker now is that Trump hates both Ryan and McConnell, and they don't much like him either.
But Trump could not, for the life of himself, get out of his own way.
Exactly. I still don't believe that him falling out with so many of his key subordinates/cabinet members are evidence that they were "bad picks". I think a lot of them were actually good appointments, but Trump simply wouldn't listen to good advice, was unreasonable, and therefore a terrible guy to work for. He now spins them all as bad picks -- though the alleged fault of his advisors rather than himself -- but the truth is most of them were likely no different from the series of lawyers who have abandoned him thinking "I can't work for this guy anymore."