I think Richie Mathers was on our books as a schoolboy too, before going to Leeds. His career path tends to involve rejoining Warrington every few years
But if you discount the players that were only briefly on the books as a schoolboy and focus on players who actually spent time in the U18 or U21 teams, there haven't really been any stories of players we let go who went on to show us what might have been.
We've actually done better the other way round, with young players who other clubs have let go to us early in their careers and maybe were surprised at how they turned out with us: Lee Briers, Ben Westwood, Simon Grix, Chris Bridge.
In the case of Westwood and Grix, they weren't really let go, they were signings forced by financial pressure and relegation, but I think Wakey may have fought harder to keep Westwood if they'd have known how he would turn out and that Gareth Ellis was heading to Leeds a couple of years later. Simon Grix joined us with relatively little hype around him.
Briers and Bridge were let go by big clubs at a time when they were likely to be back ups for the foreseeable future. They both became first team regulars from the off at Warrington, and they became much better players and had long careers.
In the case of all four of those players, Warrington coaches persevered with them through some bumpy times through lack of form or injury, and I wonder if they would have had the same opportunities at other clubs. Worth considering when you next hear the critique "Warrington don't know how to develop promising talent/not willing to be patient enough to give talent a chance".