Is a box midfield useful in 9v9?

A box midfield can be useful in 9v9 if it suits the players and you understand what it changes. The two deeper players can help build-up and protect transitions, while the two higher players can receive between lines. The risk is central congestion, limited width and an isolated striker. You need clear answers for where width comes from. Usually the outside defenders have to support higher, which increases their physical and tactical responsibility. I would introduce the relationships before naming the system. Can the two deeper players work on different heights? Can the higher two avoid occupying the same space? Can the striker connect rather than wait alone? It is not automatically an 11v11 idea forced into 9v9. It becomes unsuitable only if the players are serving the diagram rather than the diagram helping the players solve the game. Your central profiles suit the box, but the width issue is significant. The outside defenders do not need to stay high constantly, although they must recognise when the whole team has narrowed. You could also let one higher midfielder drift wide at times. Test the relationships in a game before committing to the shape.