They should promote whoever they think will make them successful. Unless the man is a convicted criminal, then he should be promoted based on the hopes of the 49ers and his previous success rate. Every team tries to come up with ways to show how great they are, and their promotion of him was one way to do it.
Jim Tomsula has a long relationship with the team and first-hand knowledge of its players. He is familiar with the team's strengths and weaknesses. Tomsula has been the defensive line coach since 2007 and has proven himself capable in that position. He briefly served as interim head coach for one game that his team won. He has earned the respect and admiration of the players and fans and is well-equipped to handle the job. His knowledge and experience will prove valuable to the team.
Jim Tomsula was an excellent choice for the 49ers. Promoting a coach already within an organization as opposed to bringing in an outsider is always positive for not only business but organizational morale. The team will benefit as well, as Coach Tomsula is already familiar with the team's style of play and comfortable with other coordinators. This should be an easy transition for the 49ers. Tomsula is ready to step into the head coach role.
I honestly think it is hard to say if the promotion of Jum Tomsula will make a difference for the 49ers. I honestly don't think we'll have this answer until a good way into the next season. I have my doubts he'll make a huge impact at this point, but one could always hope.