The former 14th overall pick was traded to Pittsburgh after it was clear that he wasn't in good favor with the team anymore. While he had previously been excited to join the Jets, it was becoming clear that he wanted out. Unfortunately, his exact reasoning for wanting out is utterly ridiculous and is downright offensive to the intelligence of Jets fans.
According to Kevin Cheveldayoff, McGroarty told the team that putting on the Jets jersey just didn't feel right for him. It seemed to give the young talent anxiety, and he ultimately wanted to go elsewhere.
As you can imagine, this reasoning has led to a whole lot of ridicule online. Jets fans were particularly unenthused about the whole thing, noting that McGroarty should be ashamed of himself. Others said "good riddance." At the end of the day, Jets fans and the organization itself only want players who are genuinely interested in the franchise.