Carragher said: "Jamie Redknapp has been raving about him. Besides Thierry Henry he has been as good as any striker in the Premiership in the second half of the season from Christmas.
"He was outstanding even against the top teams. His performance against us at Southampton was probably sufficient to get him a move. He was outstanding and very hard to handle.
"He was a nightmare to play against personally and he scored at the back post. He got in behind me. It was my fault.
"Peter gave them a fighting chance of staying up with not only the goals he scored but his hold-up play.
"It is a little bit of a different pressure at Liverpool. He is playing for a top team but hopefully he can cope with that."