Cruz wins in closed primaries.
Texas was an open primary, and Alaska was a caucus. Other problem is that as the race moves to other states, Cruz's "very conservative" and "evangelical" voter groups-- the only ones he appeals to-- will be smaller and smaller proportions of the electorate, and even then, he's not guaranteed to win them, since he lost them in South Carolina, Nevada, Georgia, etc., and only won them in Texas, his home state, and Oklahoma. Look at how bad Cruz did in Vermont, Massachusetts, and even Virginia, where more moderate voters prevailed. His numbers turn from being close to Trump to far away from him-- because Cruz literally doesn't appeal beyond his narrow voter group.
As far as I know Cruz (OK) and Trump (AR) have each won one closed primary. I guess we will see if this conventional wisdom turns out to be false as most conventional wisdom does.
I also just realized that Arkansas was a closed primary, which Trump won.
The latest Cruzer meme “We always win Closed Primaries, so therefore we’ll win more moderate states!” goes burning down right away.
Texas isn’t a closed primary.