Tuesday, January 13, 2015

Hot-Shooting Guards Lead NC St. Over Previously Unbeaten Duke

One of the biggest upsets of the current men's college basketball season occurred this past Sunday, as unranked North Carolina State handed No. 2 Duke its first loss, 87-75. Key to the Wolfpack's win was the three-point shooting of two upper-year guards, senior Ralston Turner and junior Trevor Lacey.

Turner hit three three-pointers in a little over two minutes (between 16:58-14:48) during the second half, to help NC State maintain a narrow lead. A bit later, Lacey hit a couple of threes and a two during a 22-5 run as the Wolfpack expanded a 50-48 lead to a 72-53 advantage (play-by-play sheet). Duke rallied some, but couldn't catch up.

Turner ended up 4-of-7 from behind the arc during the day, whereas Lacey went 5-of-7. As it turns out, these guards' long-range success has been building over the past month. In the following graph, I show Turner and Lacey's three-point shooting percentage game-by-game this season, with the larger basketball data-points (orange for Turner, red for Lacey) reflecting greater numbers of three-point attempts in a given game. You may click on the graph to enlarge it.

The graph should be read from bottom to top, in thin slices. In the Wolfpack's season-opener against Jackson State (JSU), for example, Turner shot 1-of-4 (.250) from behind the arc, whereas Lacey shot 3-of-5 (.600).

If you're an NC State fan, what you want to see are large-sized basketball icons high up in the graph, meaning that a player launches a lot of three-point attempts and makes a healthy share of them. Turner has indeed provided several large orange basketballs, shown in the shaded area representing shooting percentages between .400-.700. Against Tennessee, in fact, Turner made eight treys on an amazing 17 attempts, a .471 clip (click here for Turner's game-by-game log).

Lacey doesn't necessarily shoot many threes in a game -- indicated by the relative dearth of large red basketballs -- but when he fires from downtown, he frequently hits. In six of his last eight games, he has shot .500 or better from behind the arc (click here for Lacey's game-by-game log).

Two additional trends are worth noting. First, for the past month, cold-shooting games have been very rare for Turner and Lacey (see the blue notation on the graph). Second, the two players' shooting accuracy from game to game appears to be correlated. The good news is that, if one of them is shooting well in a game, the other tends to be, also. The bad news, however, is that if one is shooting poorly, so is the other likely to be. For those with some statistical training, the Pearson correlation between Turner and Lacey's three-point shooting percentage is .45 (where 1.00 is the maximum).

It's possible a sort of "contagion" operates between Turner and Lacey, where one player's shooting level in a game (good or bad) rubs off on the other. Another possible explanation is that good defensive teams shut down both Turner and Lacey, and bad ones let both of them shoot the deep ball well.

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