Carragher says the summer arrival from Bournemouth doesn't deserve a starting spot at this stage in his LFC career.
Asked if time out of the XI can be good for Kerkez, Carragher told Sky Sports: "No, but I think it's working for Liverpool in that I don't think he should be playing every week.
"You've got too good a player in Andy Robertson who needs to play games as well. I think when Andy Robertson's played, he hasn't played as much as Kerkez, I think you'd probably say Andy Robertson's performances have been better than Kerkez's.
"He's found it tough, it's been a struggle for him. He's a young man, but he will have to improve in the second half of the season, there's no doubt about that."
He added: "I always remember speaking about Trent Alexander-Arnold, who Liverpool have missed enormously of course, and said it's like having Kevin De Bruyne at right-back.
"Sometimes, when you watch Kerkez, it's like having Darwin Nunez at left-back, it's just a bit mad. There's no real thought process, what's he doing with the ball, how's he connecting with other players, it's just head down, run. He never gets his head up and actually plays passes."