Via Deadspin, here's a fantastic breakdown of the 1-3-1 zone from Mgoblog. Since John Beilein, Michigan's new basketball coach, is a primary practitioner of the 1-3-1, Mgoblog explains what it is, what its strengths and weaknesses are and how it might work at Michigan.
For a taste, here's Brian's assessment of why Beilein runs the 1-3-1:
I'm of the opinion that Beilein prefers the 1-3-1 zone because it covers up for the athletic deficiencies he's been forced to operate with his entire career. There's only one guy who really benefits from being a gazelle-type athlete, and that's the guy charged with the Sisyphean task of running the baseline. Everyone else has to be smart, aware, and well-coached. It also helps him run a small lineup on the other end of the floor without getting hammered for it on defense, as the zone defends the post mostly with quick hands, quick doubles, and the elimination of entry angles.
The post also contains great links to publications like the American Basketball Quarterly (who knew?!), addressing how one beats the 1-3-1. Reading the post is a reminder of how lacking most in-game analysis is. I have been watching basketball for thirty years, and I have never heard a broadcast explain as clearly how any particular zone defense works and what its purpose is as well Brian explains the 1-3-1 here. I have heard announcers talk about momentum and effort and motivation and attitude about a billion times. But, in terms of explaining what coaches actually teach their players and why, except for the great Hubie Brown, we almost never get that. Mgoblog's latest is a vivid reminder of what we're missing.