A lot of that -19 is from playing with Athanasiou and Filppula. They have been horrible this year. They lead the team in worst +/-, and Fabbri got stuck on a line with them, when he first went to Detroit. There was a 9 game stretch with them when he was -14. He was putting up points, but on the PP with Bertuzzi and Larkin. His line with AA and Filppula was getting wrecked 5v5.
I am not saying he was great defensively, but he definitely cannot carry a whole line defensively. Athanasiou and Filpulla were bad +/- before Fabbri, they were bad with Fabbri, and they have been bad after Fabbri. Fabbri's +/- has normalized since he was put with Larkin and Bertuzzi for 5v5. He's only a -3 over the last 12 games. His GF% at 5v5 is actually >50% with both Bertuzzi and Larkin. Its 26.09 with Filpulla.