DOES SH% INCREASE WITH AGE
Theoretically, shooting percentage should go up as a player ages, presumably hitting a peak in his mid-20s.
What is observed is that
shooting percentage is essentially constant from Age 19 to 26, and then it begins a long, slow decline.
What does increase, however, is the number of goals scored per game – because the number of shots taken per game goes up much faster than shooting percentage drops.
If a player has been in the NHL for a few years and his shooting percentage goes way up one season, there is absolutely no reason to believe that it represents a change in ability – most likely it’s a change in usage or just a case of making his shots in one particular season. It is certainly not something that we expect based on aging curves for typical players.
HOW LONG UNTIL SH% STABILIZES
How many shots does a player need to take before we can separate the talent from the randomness?
5-on-5 Sh% stabilizes for forwards at about 375 shots while 5-on-5 Sh% for defenceman begins to really stabilizes around 275 shots.
In general, after about 223 shots, the reliability crosses the 0.707 threshold.
We now know that at 223 shots a player's shooting percentage is about 50% skill and 50% luck, which is still a lot of noise. We have to get about 400 shots before we really see a player's talent begin to shine through.
This once again demonstrates how easy it is to be fooled by small sample sizes. While 223 may seem like a reasonable estimate it should be noted that only 40 players last season (2013-2014), or just over 6% of the entire league, record more than 223 shots.
This all goes to show that it does take quite a bit of time for a player's shooting percentage to stabilize.
Many are quick to reach assumptions about a player's actual ability simply based on a single season which we can see here rarely makes sense when the vast majority of the league will have taken so few shots that separating the signal from the noise is incredibly difficult.
There is definitely talent at the heart of a player's ability to score goals, it just takes some time for that talent to truly become evident.
SHOT RATES AND AGING
When projecting the growth of young players: people expect their young forwards to start shooting more. But is that a fair expectation?
A kid breaking into the NHL at 18 or 19 will see his shots per game increase by over 40% over the next five years
But, how much of that is from increased ice time and how much is from an increased shooting rate?
Players’ shot rate scarcely changes at all – from when a player breaks into the league at 19 until he peaks at 23, it’s only going up 2-3% per year, enough to account for about a half-goal per year from a 20-goal scorer.
In other words, the >40% increase in goals per game that Hawerchuk saw between 19 and 24 years old is primarily the product of an increase in ice time of around 25%, with much smaller contributions from shooting percentage (~5% increase over five years) and shot rate (~10%).
If you want to predict a young player’s goals, start with a good estimate of his ice time and make small modifications from there.
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