John Sutton, another good example. Scoring regular for us but went to Hearts and didnt cut it there. Came back to us and started scoring regularly again.
Definitely a lot depends on your team Mates and what style/tactics your team plays.
Perhaps a similar situation for Watt, absolute standout player in our team but would he excel if he moved to Rangers?
However, bottom line, individual will have much better take home pay after a transfer. Other consideration (or gamble) is wait longer to move amd make even more money after a transfer.