The AC Milan midfielder only made one substitute appearance for the Gunners in the EFL Cup before joining Italian side Empoli, but Bennacer has since become one of the first names on the team sheet at San Siro.
Since arriving at AC Milan last summer, Bennacer has already made 51 appearances for the Rossoneri and boasts four assists to his name this season in all competitions.
According to Calciomercato, Arsenal chiefs do not understand how the Algeria international was allowed to head for the Emirates exit door, with the Gunners desperately crying out for creativity at the moment.
The report states that Arsenal agreed a buyback clause with Empoli, but then-manager Unai Emery decided against bringing Bennacer back to North London, allowing Milan to swoop in and sign the 23-year-old for €16m (£14.4m).
Bennacer's solitary appearance for Arsenal came in the 2015-16 EFL Cup, with the former Gunners man coming off the bench in a 3-0 defeat to Sheffield Wednesday after Theo Walcott and Alex Oxlade-Chamberlain both sustained injuries.