I don't know. From everybody I talked to who switched from R to D in '18, it wasn't about being disappointed that the Republicans hadn't overturned Obamacare, which had, by that time gone above water in approval, it was about the dislike for Trump the person, and his harried policies. Now, a lot of that was unfair and due to shitty media, but it is what it is.
Nevertheless, regarding the Tea Party and Trump having the major accomplishments in that period, that is definitely true, but it probably had less to do with their outsider status and more to do with the arrival of each in government changed the power dynamic and allowed for different results. In the first case, it went from all D to a stopper in the house, and in the second case it went to all R. Still, I'd argue that the Tea Party and Trump were successful in getting to power for exactly the reason I suggested above, they offered a different vision. The tea party, in fact, appealed electorally to many of the same voters I am talking about, middle class, suburban women who worry about education and debt. Unfortunately, while Trump brought in some non traditional Republican voters, he bled the ones the Tea Party cultivated, which is ironic in that they were both "outsider" movements, as much as a Karl Rove supported movement and a man who had been a famous billionaire for three decades could actually be considered outsiders.
The point being, neither of them gave up, complained about unfairness and screamed about the "Commies." They offered a vision that people liked and had a strategy for communicating it, which is the only way forward in politics.