Hi, I have been lurking here for a few years now and i think this is a good time make my first post since you guys are talking about football/soccer(huge fan)
First of all, i really like Jinbei but i don't think he will be joining the crew so i wont have him in my team. Now in football/soccer the goal is to protect your goal(no pun) and score on your opponent's goal(at a glance, it is a lot more complex if you look into it) and i think that in OP it is like a ship or base. Now to my team…
Goalkeeper: Franky, i think he fits this perfectly because like i said, the goal corresponds to the ship and Franky being the shipwright and taking care of the ship is a lot like a goalkeeper protecting his goal.
Center backs: Monster Chopper and a new crewmember. CB's are usually tall and strong, they are the last defensive line and i think Monster Chopper fits this category nicely like someone had already pointed out. Other than Chopper i don't think he have someone in the crew currently that fits here.
Full backs: Brook and a new crewmember. Full backs are well rounded, they attack and defend and are good at adjusting to different situations. They usally overlap and linkup with the wingers and i think that resembles Brook, he could for example support Zoro since they are both swordsmen(Zoro is one of the wingers) And then i think a new crewmate would be the other full back, someone who specializes in hand to hand combat that would compliment Sanji since i have him as the other winger(I would love a martial arts girl with a chinese theme, maybe from the happo navy :P)
Midfielders: Robin, Nami and Usopp. Midfielder role's can vary alot, a simple description would be that they are the ones that pull the strings and control the game(referred to as Maestro's). They are often intelligent and in a battlefield they would be the strategists and i think that Robin, Nami and Usopp are the most intelligent members. There is usually one midfielder that is a more defensive that covers a lot of ground and i think that Usopp would fit here with his plants.
Wingers: Zoro and Sanji. Whenever there is a fight, M3 are the main attack force that charges in first and that resembels how the attackers run at the other team in football/soccer.
Striker: Luffy, like i said M3 always charge in but luffy is always first and he has sanji and zoro by his side just like in football the ST is always at the lead with the wingers on his side and he is the one that strikes(again no pun) down the main enemy.
Could have gone into a lot more detail but i have an exam tomorrow and sorry for my english
PS: i used 433 since it is the most common formation