When the Pistons scout upcoming opponents, they look at the most relevant information – which is the most recent information. They look, specifically, at the last five games to gauge lineup combinations, tendencies, strengths and weaknesses.
I get examining the last five games for lineup combinations and tendencies and then plugging in season-long data. But strengths and weaknesses from just the last five games? That seems like way too small a sample, especially when schedule strength can swing wildly during such a short stretch.
Kevin Pelton, back when he wrote for Basketball Prospectus, tackled the question of when data becomes significant:
Taken together, all three measures suggest that performance starts to flatten out somewhere around 25 games or so. If I was forced to put one number on when results become reliable, that would be the point, when two years ago teams were on average within two points of their final differential, adjusted or otherwise.
Player performance tends to stabilize a bit more quickly. Historically, analysts have used three benchmarks as cutoffs–250, 500 and 1,000 minutes. A starter can get to that first round figure, the smallest threshold at which I would ever seriously consider player performance, within the first couple of weeks of the season.
The interesting thing about player statistics is that there are a variety of different denominators, which means they stabilize at different rates. The denominators on rebounds (available missed shots), assists, steals and blocks (team plays) are so large that they tend to be highly reliable over small samples. The same is true of player tendencies (usage, and the percentage of plays used on twos, threes, free throws and turnovers). We see far more volatility in shooting statistics, since their denominators (shots attempted) are much smaller–especially in the case of three-point percentage. So it’s worth casting a warier eye toward hot shooting starts than players dominating in other ways.
It’s impossible for me to say how much the Pistons rely on their opponents’ last five games, so this might not be problematic if they use this info as a small piece of the puzzle. But it sounds unreliable, and in a season when Lawrence Frank’s team has routinely been out-coached, might this strategy be a factor?
Tags: Lawrence Frank