A recent twitter discussion sparked an interesting discovery: MLS coaches do not have very much professional head coaching experience. Like, at all. In fact, as of this writing a full 74% (14/19) of MLS head coaches are at their very first professional head coaching job (I include lower division head professional experience but not head college experience). Quite honestly, this is an astoundingly high number for any professional league. In fact, of the five coaches who held previous professional positions, only the Columbus Crew's first year coach Gregg Berhalter got his professional start outside of MLS (Hammarby).
It is important to understand that MLS is a very unique league in the world of professional soccer, and many foreign coaches (Gullit, etc.) have struggled with concepts like the draft, allocation money, and salary budget constraints, in addition to the cultural nuances of the North American sporting culture. Therefore, it is not necessarily a bad thing from a team's perspective to hire someone who understands MLS' unique framework. However, I think it is fair to say that eventually the league will need to adapt in its coaching hiring practices if it wants to be one of the leading leagues in the world. Obviously, much of this adaption will be down to how much money teams are willing to spend on veteran coaches, which is something the majority of teams are neither required nor willing to do. Nevertheless, the comparison between MLS and other leagues is quite jarring.