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March 21, 2012

Kendall Marshall’s Plus-Minus

Filed under: Uncategorized — Kevin Pelton @ 3:37 pm

Some two days before North Carolina faces Ohio in St. Louis to advance to the Elite Eight, we still don’t know Kendall Marshall‘s status for this weekend. The Tar Heels’ sophomore point guard underwent surgery Monday to place a screw in the fractured scaphoid bone in his right (non-shooting) wrist, but whether Marshall can play with the injury remains uncertain.

In the wake of the injury Sunday night, pessimists immediately wrote off North Carolina’s title hopes. That left cooler heads like Ken Pomeroy and our own John Gasaway to remind everyone that even if Marshall can’t go, the Heels have a fine assemblage of offensive talent that could still reach the Final Four on its own.

To try to assess the impact of Marshall’s possible absence, I turned to the plus-minus data available at Unfortunately, not every game is available–why it’s still so difficult to get uniform play-by-play in big-time college hoops in 2012 is a rant for another day–but the numbers does have show Marshall’s value to North Carolina’s offense.

                W/MARSHALL              NO MARSHALL             DIFFERENCE
Off40  Def40  Net40    Off40  Def40   Net40    Off40  Def40  Net40
Season       82.9   68.3   14.5     72.6   78.0    -5.4     10.3   -9.7   19.9
Since 1/26   83.0   68.2   14.8     51.9   69.8   -17.9     31.0   -1.6   32.6 

Over the course of the season, the Tar Heels have scored 10.3 more points per 40 minutes with Marshall on the floor. Intriguingly, his impact rates just as positive at the defensive end of the floor. The more relevant numbers here, however, are the ones since Jan. 26, when North Carolina lost starting shooting guard Dexter Strickland–who also served as Marshall’s backup–to a season-ending knee injury. During the last two months, the Tar Heels’ offense has collapsed every time Marshall has left the floor.

In part, these numbers are limited by garbage time, which is much more of a problem with college plus-minus than in the NBA. Basically, because so many games are lopsided, the numbers are biased. Much of the time Marshall has spent on the bench, especially since Strickland’s injury, has come with deep reserves in the game. So I went through and looked only at the stints Marshall has rested from games over the last two months. Clearly, Roy Williams has been strategic about getting Marshall out of the game. He typically does so right before a media timeout, and I suspect if we had possession data it would show that Marshall has rested more on defense than offense. The abysmal rate at which North Carolina has scored without Marshall in that span shouldn’t be taken too literally.

Still, even the longer stretches Marshall has sat out have been painful for the Tar Heels. Take their Feb. 25 game at Virginia, when Marshall was on the bench for nearly three minutes during the first half. North Carolina mustered just two points in that span with Harrison Barnes, John Henson and Tyler Zeller all on the floor.

Beyond that, the way Williams has used Marshall is a data point in and of itself. In four of the last 11 games, Marshall has played the entire second half. The heavy minutes Marshall has logged are an indication that Williams doesn’t trust his other options (true freshman Stilman White and defensive specialist Justin Watts, who is not really a point guard) in close games. White and Watts will be more prepared if they have to replace Marshall this weekend, but the Tar Heels will still miss their starting point guard. I don’t think North Carolina’s title chances go to zero without Marshall, but they’re a lot closer to that than to favorites to reach the Final Four.

You can contact Kevin at Follow him on Twitter at @kpelton.

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