The Viola suffered their second consecutive Serie A defeat, falling 2-1 at home against Sampdoria on Friday evening.
“Compared to the first two games, there was a step backwards in terms of performance, even if we had started quite well,” the coach told Sky Sport Italia.
“We made a few too many misplaced passes in midfield and this created excessive tension within the squad. It should not happen. We conceded an entirely avoidable goal that we cannot afford to gift. It’s a pity, as we tried until the end to get it back on track.
“Franck Ribery was a big loss, as were others, but that cannot be an alibi. We’ve got to realise these errors cannot happen.”