The 20-year-old is relatively unknown in England, so ESPN FC asked football writer Chris Paraskevas, who follows the Greek league and national team, to provide some insight on the defender. Here are five things to know about the new Gunner.

He has size and agility on his side

The first thing that stands out about Mavropanos is his size. At 6-foot-4, he is slightly taller than Liverpool's new signing Virgil Van Dijk and shares some other characteristics with the £75 million Dutchman as well.

"One of the things that makes him an interesting prospect is that he matches his size and his physicality with his speed," Paraskevas said. "He's super agile for a guy that size. You would expect him to be kind of lumbering and clumsy when you first look at him, but he's actually quite nimble."

Arsenal's defence has often been criticised for not being physical enough, but Mavropanos could easily change that.

"I think Arsenal need a player who will sit at the spine of their defence and bring that uncompromising physical presence," Paraskevas added. "Mavropanos has a lot of potential and he could be the type of player that Arsenal needs in the future."

He could be the next Kostas Manolas?

Arsenal were among the clubs heavily linked with Roma's Greek defender Kostas Manolas in 2016, before buying Shkodran Mustafi instead. But in Mavropanos, they may have unearthed the next Manolas for a fraction of the price Roma were asking for.

"The former academy director at PAS Giannina who spotted Mavropanos at his boyhood club said recently that one of the things that stood out for him is that he now really resembles Manolas in the way he has developed. He is one of those guys who combines strength, speed and size," Paraskevas said.

"However, Manolas had much better pedigree even before leaving Greece. Mavropanos is a relative unknown from a smaller club. But I think Wenger is scared of missing out on the next Manolas. And £2m is a pretty small price to pay given that Manolas is now worth a lot more."

He has an aerial threat

Unsurprisingly, Mavropanos' height also makes him quite the aerial threat. He has netted three league goals this season, all of them headers from set pieces. But he's relying on more than just his physical traits to dominate in the air.

"As much as his size, it's the timing of his jumps. He has a natural ability to hang in the air and times his jumps, whether in attack or defence," Paraskevas said.

"But especially in set-piece situations going forward, his ability to jump combined with his size is what makes him such a threat. With a bit of tutoring from Arsenal's more experienced defenders, I think he can actually become a bit of a weapon."

He still needs to develop

Wenger gave a curt assessment of Mavropanos on Wednesday, saying "he's not ready to play for us yet." And there are still plenty of aspects the 20-year-old needs to work on before being ready for the Premier League.

"He needs to improve his technique and the tactical part of his game. But he's a very fast learner," Paraskevas said. "Another thing is the ability to deal with pressure. PAS are a small club in Greece and not a lot of is expected of them in the Greek league. So he needs to learn to deal with the pressure of being at a bigger club, and an environment where the pace is faster both on and off the pitch."

He will learn from a loan spell in Germany

Mavropanos is expected to be sent out on loan to Werder Bremen for the rest of the season, which could be a perfect place to grow.

"It's an absolutely necessary move to send him to Germany. Greek players have really done very well in Germany, especially defenders in the last few years," Paraskevas said. "Werder Bremen have also traditionally played a fairly attractive style of football that is similar to Arsenal's so it makes total sense.

"In Greece you have a lot more time on the ball than you will in England, so his decision making is something that will have to improve dramatically. But I think Germany is a good learning ground for that."