I will give it a shot. Average Americans know Donald Trump. They know very little about Cruz, Rubio, Kasich, etc. Many of the votes were choices between an unknown and a "hell no." Many of them would still prefer that last unknown standing.
“They know very little about Cruz”
Cruz has been running for president for about a year. He has spent millions of dollars campaigning. If voters don’t know who he is after campaigning in their states for months and saturating the media, then he needs to give it up.