Except tha Trump is a total outsider and Cruz is not
That made it hard for him, and in states like Washington (where I live and attended the caucus) there was lot of shenanigans that went on to push him over the top.
My take is that the rules were altered so that a candidate like Mitt could win more easily with 40% or so. States that had proved troublesome had their rules altered.
For instance, Washington eliminated our caucus (which the Ron Paul forces had learned to dominate) and replaced it with a primary.
The unintended consequence is that a real outsider (Trump) has been the one to get to 40%, and he may well win the nomination with only that level of support, due to the odd rules.