How much of the NHL flips over a year to year and multi-year basis?

[WarriorofTime]

I'm curious if anyone has ever looked into the personnel of the NHL and figured out, on a games played basis, what percent of the NHL flips over each year, as in players that were in the NHL one year and not the next (and vice versa). I'd be curious what this looked like over longer periods of time as well, like how many players that were in the NHL ten years ago are in it now, same with 5 years. Presumably by 20 years you'd see the entire league flipped over (outside of the extreme case)

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[666]

I'm curious if anyone has ever looked into the personnel of the NHL and figured out, on a games played basis, what percent of the NHL flips over each year, as in players that were in the NHL one year and not the next (and vice versa). I'd be curious what this looked like over longer periods of time as well, like how many players that were in the NHL ten years ago are in it now, same with 5 years. Presumably by 20 years you'd see the entire league flipped over (outside of the extreme case)

I once read somewhere that each team retires two players and replaces them each season on average but I don't know where I read it and it was a decade ago.

 

[Hockey Outsider]

I'll present this as preliminary data to get the conversation going:

I looked at the amount of turnover in the NHL, starting with the 1949-50 season. I compared the rosters in the current and following season only (ie 1949-50 to 1950-51). I arbitrarily decided that a player needs to play in at least 10 games in both years. This is for skaters only (no goalies).

This was a difficult report to generate and it's likely there's random errors in the data. Without doing a deep dive, I'm not sure how much this affects the results.

With these disclaimers in mind - the long-term average is 81% (which means there's 19% turnover).

There was only a single season with less than 10% turnover. That was 1966-67. That's not a surprise - the NHL doubled in size the next league. Virtually everyone who was good enough to play in the six team league was able to get a spot the next year.

The two seasons with the most turnover (right around 25%) are 1951 (no idea why) and 2004 (lots of older stars from the previous generation couldn't withstand a year away from the rink in their 40's and/or weren't fast enough to keep up after the lockout when speed was emphasized - Lemieux, Messier, Yzerman, Hull, Francis, Robtaille, Oates, Mogilny, Andrehychuk, Damphousse, MacInnis, Stevens, Leetch, etc).

 

[Michael Farkas]

In that raw data that you needed to generate this (awesome, by the way), is there an age column? Is there a "is rookie?" flag by any chance?

 

[Hockey Outsider]

In that raw data that you needed to generate this (awesome, by the way), is there an age column? Is there a "is rookie?" flag by any chance?

Unfortunately not. I have that for some years, but not all.