The Brazilian was wholly ineffective in the 2-0 loss to Newcastle United on Sunday.
The Brazilian forward was a big money singing by former manager Brendan Rodgers in the summer, but has so far failed to impress at Anfield.
His performances had looked like they were improving under manager Jurgen Klopp, with a fine display in the 4-1 win over Manchester City his best in a red shirt.
He has again struggled in their last two games though, and Aldridge has criticised him for pulling out of a 55/45 challenge, saying Liverpool fans will not accept that behaviour.
“Roberto Firmino is playing as if something is wrong, mentally and physically. He’s been absolutely redundant the last two games,” he told the Liverpool Echo.
“It can’t just be the fact his mate Coutinho has been missing. The Brazilian also pulled out of a challenge that was 55-45 in his favour.”
“Liverpool fans won’t accept that. I’ve been going for 50 years and I know it’s unacceptable. If the ball is there to be won you win it. He’s going to have to learn to get stuck in.”
Given the money Liverpool paid for Firmino in the summer, there is no denying he has been a disappointing signing so far.
He arrived from Germany to much fanfare and expectation, but has so far failed to live up to either with a series of disappointing displays.
Indeed, a return two goals and one assist in twelve games are far from what the club would have expected and they will be hoping he can turn it around dramatically in future.