By my standards, the last bad game Lucho had was at Real Sociedad on Jan 4, when he failed to start both Messi and Neymar.
The team is improved this season in almost all areas, so you have to give Lucho credit. Defending set pieces and defense in general are clearly better. The team has had its ups and downs, as happens over such a long season, but Lucho deserves a lot of credit that they are in such fine form now, at the most important part of the year. He has been getting really good play from pretty much everyone he is giving playing time to, and not one player seems burned out.