The contention in the title, for starters. It's impossible for a President to be effective if he can't make excellent deals. What made Reagan great?..the ability to form a consensus. A consensus is a deal.
There ya go.
Reagan made very few deals with Tipp. Their relationship was friendly after working hours and they never discussed politics off the clock. I remember Tipp saying “over my dead body” on a bill he opposed, and Reagan saying with a smile, “Well, that may be.” Trump is miles away from Reagan in style and substance.