That's nice, but if it's true, I'm wondering when Arizona remembers a UFA being traded for an established young player. Has it happened in Chayka's lifetime? What makes Hanzal different?
There are a few examples I can think of off the top of my head. Some teams have been willing to part with established young players for UFA trades, though I agree that is rare.
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Kovalchuk returned Bergfors (who had 21 goals that season) though it was Kovalchuk, and there other pieces on either side
Legwand returned Jarnkrok - who was not "established" but about as close to ready as anyone could have considered a prospect.
Kim Johnsson returned Cam Barker (but Leddy was part of the trade too)
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It is generally accepted now that you should expect a much bigger return if you make the trade when the guy has a year to run (e.g. Ryan, Lucic, O'Reilly, Yandle) but I don't see any reason why a prospect-rich team like Arizona couldn't do deal structured like the ones above (Hanzal + prospect for young player + mid round pick) or bundle him with Stone for a bigger return.