Probably more common than you think, just tends not to happen the spring immediately after being labelled a 45 FV.
Maybe that rank was bogus though. His stuff doesn't seem that special when you consider the shape of his pitches.
Also, Zulueta is older than your typical prospect.
Lots of the flop 50+ FVs get dumped but they just tend to get traded for cash first, and then a year later DFAd.