Nicky Bissett, looked great but then suffered a broken leg and was never the same player again.
Could say the same for Adam Hinshelwood. Called up to England U21 squad, but injury prevented him from going and knee problems got rapidly worse leading to him returning early.
First few that come to me.
Robert Codner
Leon Knight
Ian Chapman (great for us, but perhaps should have moved on earlier in his career especially as the club went backwards)
Jake Robinson