The 32-year-old brought his second Chelsea spell to an end when he joined London rivals Arsenal for a fee around £8 million in August.
Luiz was set to stay at Stamford Bridge initially but after an open conversation with head coach Frank Lampard, the Brazilian was told he was not part of the club’s plans for 2019-2020.
Since his shock move to Arsenal, the former Benfica and Paris Saint-Germain defender has come under intense pressure with his poor performances at the Emirates Stadium.
Cascarino has named Luiz as the worst signing of the summer, in his latest column for The Times, and insists Chelsea were bemused at how Arsenal were so eager to sign the veteran center-back.
"When Arsenal bought the Brazil defender in the summer for £8m I know that Chelsea’s reaction was: ‘Wow, they’ve taken our poorest defender,’ the former Chelsea, Celtic and Aston Villa forward said.
"You have that familiar image of him chasing after a forward who has got behind him: opponents always know that the 32-year-old will give them space by wandering out of position.”
"He is a fine footballer who sprays the ball around well but for a player with so much experience his defending is not good enough."
Luiz is likely to line-up for Arsenal, when they welcome Chelsea to the Emirates on Sunday for their last game of the year.
