Premier League 2018-19: 3 Reasons why Arsenal won't win the league

#2 An unreliable defense

Emery has spent most of his transfer budget to improve the defense, with the arrival of Stephan Lichtsteiner, Bernd Leno, Sokratis Papastathopoulos and Lucas Torreira aimed at building a solid backline.

In the center back position, Arsenal have Sokratis, Holding, Koscielny, Mavrapanos and Mustafi. But while Emery has a pool to select center-backs from, Holding and Mavrapanos are both not ready to play regularly.

Chambers, meanwhile, had shown promise to be a regular starter during the pre-season but he was sent on a loan to Fulham.

Sokratis is expected to be a starter as Koscielny recovers from his injury but the defender will need to adapt quickly to the Premier League, as a mistake in his position can be quite costly. And Mustafi will have to prove to Emery that he is able to defend without any major mishap.

Chambers was expected to play a bigger role this season.

In left back position, the two main contenders are Nacho Monreal and Sead Kolasinac. Monreal is expected to start ahead of Kolasinac, who was named in the Bundesliga team of the season before his arrival at Arsenal.

Kolasinac seems better going forward than defending, and looks vulnerable against tricky wingers. That will leave Monreal to continue in his position till Kolasinac improves defensive aspect of his game.

Currently, both of them are injured and that has left another hole in an already fragile defense.

Monreal should be able to retain his position as Arsenal's left back ahead of Kolasinac

In the right-back position, Arsenal had Bacary Sagna who did his job perfectly for many years. But ever since he left, the position has been waiting for a right back who does his job both in attack and defense.

Bellerin has been good since he was introduced and his electrifying run in Arsenal's 2-0 win against Bayern Munich in 2015 made him a star. But last season just didn't go right for him.

Stephan Lichtsteiner was then recruited to help Bellerin's revival, and he will also be vying for game time himself.

Overall, the Gunners' defense often looks uneasy against a high pressing team. And facing a counter-attacking side isn't one of their strengths either as they lack a speedy center half to recover in time - as seen on many occasions in their match against Manchester City.

Arsenal are also in a difficult situation with Lichtsteiner, Monreal, Koscielny and Sokratis all above 30 years of age. With the youngsters still unreliable, it remains to be seen what Emery will do to address these problems.