Every delegate to the convention was equally available to every candidate from the start. Some were allocated by popular vote, some by caucus, some by conventions at the precinct, county and state levels.
The problem is that Trump has been competing for only those delegates available via the popular vote. He either chose not to compete for -- or was ignorant of -- those delegates available via other means.
In that respect, Trump took a chance that his intentionally limited campaign could still produce the requisite majority of 1237.
In contrast, the Cruz campaign chose to compete for every delegate available to him -- regardless of how they were allocated. Successful execution of that strategy is what's keeping him in the race.
You can take the two disparate strategies as demonstration of the candidates' decision-making skills.
This is a fraud. It will not stand.