The summer departure of Cesc Fabregas threw away Arsenal's progress under Arsene Wenger, according to former Gunners midfielder Emmanuel Petit.
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Fabregas returned to boyhood club Barcelona in August, and Arsenal have subsequently enjoyed a disappointing season: they are currently sixth in the league, six points away from the Champions League places.
Petit, who played for Arsenal between 1997 and 2000 before joining Barcelona, also feels that the absence of Jack Wilshere to injury has blighted the London side's season.
"With the departure of Cesc Fabregas and the absence of Jack Wilshere, this team becomes quite predictable," Petit told the Sun. "Where's Arsenal's style of play gone? It's reduced to nothing, all those years of hard work. It's very frustrating."
Arsenal have suffered three successive league defeats, but aim to get their season back on track away at Bolton on Wednesday.