NHL Analytics: Shots, Rebounds, and Weak Signals

Another unsurprising finding — there is a big spike in the number of shots and goals due to rebounds compared to all other shots.Since we can safely say that there is a three second period after the first shot where there is a dramatic increase in the probability of scoring, we can confidently categorize all shots within this bound as “rebounds.” This will be very important to the rest of this piece.1–2–3Why are rebounds after two seconds better than rebounds after one?.This is also reinforced by the sharp drop in the number of shots at 2 seconds (think of this as the holy grail of rebounds).Now that we know “what” a rebound is, we can look at how important they are.Roughly 5% of shots that constitute rebounds lead to over 15% of the goals scored.While shots leading to rebounds make up only 5% of all shots, they make up more than 15% of the all goals scored..The closer to the box you are, the more likely a shot is to lead to a rebound, but the probability that a shot leads to a rebound is not as skewed as the actual shots taking place.This points to a hypothesis that there is not as strong as a relationship between where shots are taken and their likelihood to lead to a rebound (i.e., scoring opportunity) as some may think..Perhaps teams should focus less on getting the right shots and more on taking more shots?Good Shots vs More ShotsFrom what we have seen so far, it would make sense to hypothesize that a team that converts more shots into rebounds is more likely to win games..In fact, a higher rebound rate is associated with a lower number of wins!We also find that a higher rebound rate has a strong relationship with fewer shots taken and also see that more shots = more wins.It is essential to think about the results above in context..Perhaps a team with a lower rebound ratio in a game points to better goal tending?Keep in mind that the average number of rebounds per team per game is only 3.9..One reasonable explanation could be that over a season, a team with very few shots and a low rebound rate is indeed trying too hard to find the right shot..Conversely, a team with many shots is taking more shots (leading to better outcomes)..It could be the case that while individual game statistics are very noisy (or, indeed, almost random), we can find much better relationships at a seasonal or monthly level.The next article in the series will focus on groups of teams to better understand the relationship between shots, rebounds, team behaviors, and wins.P.S :I’ll be following this up with a code-based walk-through of much of this analysis.. More details

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