I didn't have a problem with Martinez starting all this year. I thought he was the best QB for the job, and gave the team the best opportunity to win games. McCaffrey showed glimpses, but he wasn't physically ready to be the man this year.
Next year will be interesting because if McCaffrey can put on the necessary size and can make the necessary throws, he may win the job. The most interesting aspect of McCaffrey is how well liked and how the younger players are gravitated to him. From what I have heard, the class of 2019 recruiting class is very close, and McCaffrey is one of the biggest leaders of the group. That intangible may be the thing which swings the QB job to McCaffrey for 2020.