Zappacosta started the match, with Super Eagles star Victor Moses out injured.
Antonio Conte’s men scored twice early in the first half through David Luiz and Eden Hazard, before Aleksander Kolarov’s shot was deflected past Thibaut Courtois.
Edin Dzeko’s brilliant brace in the second half, seemed to have handed the Serie A side all three points, before Hazard headed the Blues level.
Sherwood slammed Zappacosta for allowing Kolarov have a free pass down the right of Chelsea defence.
“Kolarov isn’t the fastest but he left Zappacosta for dead severally. Zappacosta allowed Kolarov too much space and time on the ball, something that Victor Moses won’t do against a player like Kolarov,” Sherwood said during his post-match analysis.