Having some core beliefs and a knowledge of how to get things done is just as important. George Bush had lots of executive experience but other than being anti-islamic, he had no core beliefs. He caved to the Dems on prescription drug coverage, allowed spending to get out of control, failed to rein in Fannie and Freddie, etc.
Ryan isn’t seeking the office, even though many encouraged him to run. That is exactly the kind of person we need.
That goes without saying, but having zero experience in running a large, hierarchical organization (as a president) is a recipe for mediocrity at best, and total disaster at worst.