Ground game is not door knocking. Ground game is personal contact via phone and internet as you describe. Have not seen much from Trump so far. He needed an organization in Iowa in my opinion.
Trump just did not understand the Caucus system and still does not as evidenced by his remarks. Trump failed to understand the dynamics of a group in a same room taking sides, he didn’t understand PEER PRESSURE at the time of voting and trial votes... Thank goodness most of the rest of the country votes by a different method.
Trump should have had the Team Cruz did to go around and cajole voters... People inside pressure groups vote differently than in a private voting boot where no one is allows to campaign any where near.. a private unpressured decision is made ... AND THAT WAS WHAT BEAT TRUMP — his lack of knowledge of the Caucus system of so called voting.