On Monday, we touched on the East and South regionals with detailed breakdowns of all first-round games with Giant Killer implications. On Tuesday, it's the Midwest and West. We also will remind you (again) to follow the Giant Killers blog for all things GK-related. In case you've forgotten, a Giant Killer is a team that beats an opponent seeded at least five spots better and doesn't come from a BCS conference. Other teams -- Gonzaga, Butler, BYU, Xavier, Northern Iowa and Temple -- are excluded, too. Check out our methodology for a full explanation. Our model generates statistical ratings that compare potential Giant Killers to past Davids as well as all Giants to the Goliaths who were slain. Those ratings enable us to predict the chances of an upset in each matchup -- and this year looks like a doozy. The Midwest, in particular, has a number of games that should make you think before going with chalk in your bracket, and they might not be the ones you ordinarily would target.