The technically-gifted midfielder, set to return from injury for Newcastle United against Arsenal at St James’s Park tomorrow, is rarely out of the headlines.
Shelvey has been an influential figure on the field for Benitez’s side over the past two years, though he hasn’t played for England since joining the club in January 2016.
National team manager Gareth Southgate ignored calls for him to be recalled ahead of the World Cup in the summer. England’s defeat to Spain during the international break, however, suggested that Southgate needs a playmaker like Shelvey in his squad.
Asked why Shelvey had so many critics, Benitez said: “Because he’s good. If he was bad, no-one would be talking about him. When he’s a good player, you can say ‘oh, I like this, I like that, but I don’t like that’. But if he was a bad player? Nothing.
“Why England? Because he’s a good player. Yes, he has to improve things, and he will become an even better player, but he has the potential to play there.
“Obviously, the manager (Southgate) knows that he has to do, but when you have a squad with midfielders, one like Jonjo is a different option.
“I’m not saying he should play every game, but he offers something different. I will say again, for me , he is a key player, because he plays in a different way. Does that mean he is perfect? No, but he’s a good player.”
Southgate has never spoken to Benitez about Shelvey, who has won six senior international caps.
“I do not need to push anyone,” said Benitez, who signed Shelvey at Liverpool in 2010 before leaving Anfield.
“I don’t like anyone pushing me. So he has his own people, but if he was asking me about Shelvey, I would say yes.
“Who signed Jonjo for Liverpool? Me. He was a young player with a lot of talent. You could see the potential there. Since then, he has played a lot of Premier League games and has more experience.
“He’s more mature and more focused on what he needs to do. He knows when he was making mistakes. If you were doing 10 things wrong with him and 20 things right, now it’s five wrong and 25 right. So he’s getting better, because he’s more mature.”
Shelvey’s temperament has often been questioned.
Benitez added: “He’s much better. He’s older, more mature. He has more experience, so he’s dealing with those situations a lot better.”
Benitez wants to see Shelvey score more goals and, more importantly, dictate games in the Premier League.
“He will score goals, because he’s good at shooting from outside of the box,” said Benitez. “That’s something he can definitely add to his game.
“But the main thing, for him, is not to score goals, it’s to dictate the pace of the game. That’s what he can add and that’s what is making him a better player.
“He has to manage the game and make the right decisions in the game. If he can do that, he can play for any team, because he has the technical ability.
“It’s just to be sure he can do all of those things, and that comes with experience, maturity and composure.”