He's good to go. Play him a lot and he will grow above 90% in no time. Maybe he can still be good for the next season. Try doing the same with all your positions little by little, as you grow in the game you will buy even better players and your team will have it's own character. Don't buy too many players in the last two weeks since there is less time for them to grow and you will find better ones on the market next season.