"There are some players who sign for top clubs and you watch them and wonder if they're good enough to make it, but that's never been the case with Morientes at Liverpool," said Carragher.
"He's a class act and you can see what skill and quality he has. We see how good his touch is in training every day and it's just been a case of him taking it into the games.
"The big question has been whether he can adapt to English football, but the real reason it's not happened sooner is really down to bad luck with injuries, as far as I'm concerned.
"I think a lot of the things which have been said about Morientes have been unfair because his biggest problem has been those injuries.
"It's not true to say he hasn't done anything. Last season he scored some cracking goals, including one against Charlton, and his first half performance in the Merseyside derby helped us win the game.
"The signs have been there before he can adapt to English football, but every time he's looked sharp he's picked up a knock. The key for him is to get a run of games under his belt and then he'd make a massive difference.
"His record at the top level is exceptional, but he's never been what you'd call an out-and-out goalscorer like Michael Owen or Robbie Fowler.
"He's a more all-round player who likes to play off defenders, so expecting him to tumble in lot of goals every week wasn't realistic.
"If he can get a run of games going I'm sure he'll score plenty and the goal he scored last night will do his confidence the world of good.
"He's probably put the most difficult chance of all away, but now he's got one, hopefully a few more aren't far away."