Power rating systems like Pomeroy's and Sagarin's distill a team's season-long performance into one number. Sometimes one number isn't enough to gauge how well a team is playing recently or to understand the ebbs and flows encountered by all teams.
Several years ago, I unveiled net efficiency margin, or NEM, as a way to measure a team's game-by-game performance on a tempo-free, opponent-adjusted basis. NEM is derived from Ken Pomeroy's adjusted efficiency numbers. Charting NEM over the course of a season shows the "shape" of a team's season in a way that a single number or even a table of numbers can't.
Let's look at the teams remainig in each region to find some hidden nuggets that might not be obvious in the season power ratings. All charts show five-game running averages to smooth out the normal game-to-game noise. Remember that NEM inherents the strengths and weaknesses of Pomeroy's system.
When Kentucky peaked, they peaked, but they've dropped off noticably over the last several games. I'd still take them to win the South, but the gap between the Cats and Indiana and Baylor isn't as large as it was several weeks ago. Perhaps, that's why...
Ohio State just took over the #1 spot in the Pomeroy ratings, and the Buckeyes are the only team with clear NEM separation over their regionmates. Wisconsin is closest to the Buckeyes (though some of that may be the Pomeroy system's affinity for the Badgers, so an all B1G regional final wouldn't be a surprise.
Nobody outside of the Dean E. Smith Center knows the (Kendall) Marshall Plan, so assessing the Heels' chances in St. Louis is tricky. Their Triangle neighbor NC State may be playing the best right now of all four Midwest teams. The Wolfpacks' NEM trendline just converged with North Carolina's, and Kansas has been trending downward since late February. At the very best, the Heels will have a limited Marshall running the show, so the first Wolfpack berth in the Final Four since the Jimmy V era isn't as far fetched as it sounded several weeks ago.
The West seems pretty wide open. Florida's surge is probably slightly exaggerated by their two strong tourney games, but all four seem to be peaking at the right time. Michigan State still seems like the favorite here.