Hawerchuk has shown that 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. What was left unanswered was how much of that is from increased ice time and how much is from an increased shooting rate. In this article, I'll take a quick first pass at answering that question before getting into the hairy details tomorrow.
I didn't want a trend to be washed out by the noise in the shot rates of people who didn't play much, so I gathered the shot rates of all forwards who played at least 700 even-strength minutes. This
seemingly arbitrary cutoff gives us about 270 forwards per year, roughly the top nine from each team. Plotting average shot rate versus age for a top-9 forward in the last four years gives this:
The striking thing here is how shallow the curve is. 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.