My question would be: What message do you send by accepting opportunistic transfers?
Now, if player X's family moves; or if he needs to spend more time on academics and less in a car; or if there's another significant off-field issue, I'm fine with it.
Being dissatisfied with the training regimen or the team's results, when you as a player opted for and contributed to BOTH: Not a good enough reason.
Purely in my opinion, of course.