His interpretation of the CB position was very different from Gomez – he knew he couldn't afford to let Werner turn and run at him, so he had to get tight and tackle early (Gomez's pace would have given him an option of picking his battles and surprising an attacker with a tackle and at times standing off and just shepherding him towards a corner). This didn't look too safe, to be honest – Virgil didn't seem to be anywhere near and any mistake would have let Werner 1 on 1. There were a couple of fairly dangerous moments, like the time when a kind bounce off Fabinho allowed Werner to have a strike at goal, but fortunately he missed.
All that said, I don't think Fabinho could have done any more than he did and unlike Lovren, who interprets the position in a similar way, he was never close to self-destructing. I would still prefer to have a 4th CB in the team, but he would have to be really good to be a better option than Fabs. BTW Klopp just said Matip will be out for "a few weeks, maybe couple of weeks." Really unfortunate that he's so injury-prone, but we have to plan ahead with this in mind.