This is my first board I have posted, and I know a lot of people out there know this topic better than I do, but I felt like it should be put in one place, because I was amazed at these numbers. I owe Undefeated Dream Season of 1992 and his "Michigan's appetite for a big name coach" post for the inspiration for this.
With the hiring of Brady Hoke, Michigan has had twelve coaches since Yost was hired in 1901. Of these, eight would fit the "Michigan Man" meme (having either played at Michigan or served as an assistant before becoming head coach). The four outliers are Yost, Crisler, Bo, and RR.
Yost and his coaching tree, plus a former player (Little, Wieman and Kipke) coached Michigan from the turn of the 20th Century into the Great Depression. Following Crisler's hire from the outside in 1938, Crisler and his tree lasted 30 years, when Bo was brought in from the outside. As we are familiar with, the Bo tree has now been in place for (at least part of) every presidential administration since Lyndon Johnson; we are quite familiar with the outlier from 2008-2010.
Four outside coaches have been hired in the last 110 years, and those four coaches were at the helm for a combined 59 years. In the same time period, eight "insiders" have been hired and have coached for a total of 61 years.
Per jmblue's edit, there have been 34 years of "outsiders" since 1926 when Yost retired after his second stint as head coach.
Not knocking either type of coach, but I had never gone through and thought about the past Michigan coaches in this light. Not sure that it means anything in context of the last few weeks other than Michigan is a very conservative place that historically resists change from the outside. Take from this whatever you like, but I found it interesting as hell to see the numbers together.