Brentford scored three times in the second half through Jaidon Anthony, Igor Thiago and Fábio Carvalho to sink Chelsea on Friday night as the side dropped to 10th in the Premier League table over the weekend.
The win was Brentford's first home victory over Chelsea since 1938 and Alonso was particularly critical of Chelsea's competitive mentality and their inability to maintain concentration for the full match as his side failed to impress once more.
Anthony's goal came from a corner as the 26 year old was left unmarked at the back post. Terry, speaking on his Youtube channel, ripped into zonal marking, which is something many Premier League teams have adopted.
“I don’t like zonal marking and I don’t like smaller midfield players picking up big centre-backs.
Terry continued later on: “It’s really not good enough. When you start looking at the stats and the numbers on this, it’s really unacceptable from our point and this is something we need to get better at.
“I know it’s the international break coming up and the manager has got so many players away, but it’s also an opportunity to give players rest and recuperation.
“It’s a difficult time for us and we’re certainly going through it at the moment.
“But when you go through these difficult moments I think the best thing to do is go, “JT, you’re marking him, he’s your responsibility and if he scores don’t look around the dressing room”, and I think go back to basics.
“Do this really well, be aggressive in those first headers. Do not allow Brentford, Arsenal, or whoever we’ve lost to in these first contacts with, don’t allow these teams to get those first headers and just head it freely back across the box for someone to head it into an empty net, this really frustrates me.”
Zonal marking is a defensive system where players are responsible for areas of the pitch, rather than being assigned a specific opponent. This means players can be left unaccounted for, exposing weaknesses in teams.
Chelsea must improve defensively after shipping 12 goals in 5 Premier League games, a shocking stats for a top 6 team.