Thursday, October 29, 2009

Two Roads Diverged In A Yellow Wood

Inter alia, the 2008-09 NBA season saw two remarkable streaks: Cleveland won 39 of its first 40 home games (before dropping a meaningless finale by one point in overtime with bench players seeing the most court time) and Jose Calderon made an NBA-record 151 of 154 free throws. After two nights of this season, Cleveland is 0-2 (0-1 at home) and Calderon is shooting 60% on his free throws, having missed two of five.

Flipped coins don't have a memory of the prior flip, and so the probability of a given outcome (heads, say) is constant over time and independent of whatever happened earlier. Five heads in a row? Your chance of another head is still 50%. Yet athletic outcomes surely are not like that. Success breeds confidence and good habits, which breed more success; alternatively, an eternally wowing streak like 98 percent free-throw completion might weigh mentally and make a man more nervous. Clearly with Cleveland and Calderon, the positive-feedback side dominated last year. Yet in the season's first bounces, these guys collapsed on the metrics wherein they kicked butt in 08-09. That truly is surprising; their "memory" is now amnesiac. Much like children who have no books during summer vacation, basketball players apparently forget what made them great while they slumber in July and August.

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