To be fair, Renteria and Lugo were both supposed to be average fielders with above average offense and some speed. The FO didn't own a crystal ball to tell them they would struggle in Boston. Scutaro is an average fielder who changed his mechanics to become a decent hitter with far better on base skills than Gonzalez. Gonzalez was a great fielder but an absolute black hole offensively. They decided to go with a cheaper and better offensive SS in Scutaro, fine move by me. Gonzalez isn't going to be keep hitting homers all season and his OB% still sucks right now.
As for Green and Hall, they are backups, and Lowrie ran into a mess of injuries that set him back/possibly ruined him. Yes, we all wish we could have some consistency at SS, but the FO hasn't done a terrible job. If only we hadn't traded our future HOF SS for Beckett... But again, that's crystal ball material...