Cruz is like 500 times smarter than Trump,
During my lifetime I have watched many people, try to lead. It is much more, and different, from a contest over who is the "smartest."
For example, a wonky professor type will drone on, and on, like a filibuster, and wind up losing most of his audience.
Alternately an football coach type, or a drill sergeant type, will issue some emotional points, and people are ready to follow.
Effective leadership is situational, in terms of who the followers are, and what the mission is.
If you want to build a refinery or a skyscraper, better have ALL of the disciplines lined up, ready to go on schedule, systems in place, etc.
And you had better have an effective leader. The leaders will usually NOT be the policy wonk.
SMART is situational.