The big controversy in Colorado really began last August when the GOP establishment on Colorado quietly switched to a caucus process. This move away from a straw poll insured that the party elite would determine the state winner, not the voters.
For whatever reason Trump seemed unaware of this rule change and did not send his own operatives in to ensure he would pick up the delegates. Cruz pounced on the opportunity and, without a state wide vote, swept up all thirty four delegates. This sparked cries of outrage for the voters but wry chuckles of amusement from the establishment. Some pundits like Rush Limbaugh seemed to shurg it off as skillfully political gamesmanship. However, other like Michael Savage and the Drudge Report were outraged by the oligarchy actions.
This insider coup does run the risk of antagonizing the Republican base in a swing state. The establishment may rue this day if November rolls around and the Colorado Republicans choose to stay home.