Really? You don't think it's fair or normal for a player to feel slighted?
If this was the film Major League, yeah. If a player was dumb enough to convey those emotions publicly, not really. Yankees probably already have a good idea what kind of person he is already though.
Cano is practically being signed as a DH. Offers nothing of great value defensively or on the base paths, something Ellsbury has been signed exclusively for. It's also the New York Yankees, where everyone has bstshit values which don't necessarily apply to the structure of other teams. Apples and oranges and overpriced sports cars.
Again, this is just a tweet which doesn't mean jack. Just the notion he would actually feel that way after his entire career in NY is a bit surprising if done for anything else other than a signing ploy.