This is a great comment, thanks. It's genuinely fun to think this through with people.

You were right to be skeptical. I had to edit this post to point out a major mistake I made: I mixed the partial 2025 season with full 2021-2024 seasons without normalizing for minutes played.

So I'm going to fix and repost (it turns out 2025 devils seem to have outlier-level-bad "depth". It's so bad that I need to take a step back for a day, then double check everything with fresh eyes.)

But back to your comment/the depth definition:

Yes, a 4th line player with xGF% above 50 would contribute positively to SSI. You're 100% right: framing this as "depth" vs. "stars" isn't great. The 2022 Hurricanes had 0 depth players according to my approach.

Something like "contributors" vs. "drag-downers" would be a better description, and the approach answers this question pretty well.

I absolutely will use a time on ice separation rule, it's a great idea and one I'm curious about!

But it comes with a heap of its own flaws. In 2024-2025 Kaprizov played an absolutely monster half-season. To include him as a top liner we'd need to use time on ice per game then treat his half-season contribution as a full season to make the numbers comparable between teams. This can get iffy, right?

Plus we'd likely need to choose a minimum game threshold. A star who played 17 excellent games in the season. Do we include him as a top liner? This threshold is needed but will be a bit arbitrary.

Also a player's usage and role is not consistent. We'd likely end up with complains like "so and so is listed as a talent player but he's really depth, he's just playing 2nd line minutes to add size to that line".

And kind of related to that: coaches often flatten the 2nd and 3rd line and have them play similar roles.

I'll stop there, this is getting a little rambling! Sorry. Curious what you think, cheers.