I believe the delegate battle has more to do with the party apparatus at the state level rejecting Trump more so than an organized effort by Cruz. At least that is what is currently happening in Missouri and Indiana. In Indiana, the party is electing delegates who are opposed to Trump. If Trump wins the states primary, they will be bound to vote Trump on the first ballot, but will not vote Trump on any subsequent ballot.
Then Trump has to go all out to win on the first round, and then all these establishment hacks like Cruz can simply go to hell......