The Spaniard’s side were beaten 3-1 by Liverpool at Anfield, despite taking the lead in the first half through Alexandre Lacazette.
The Frenchman’s strike gave Arsenal something to hold onto but their lead lasted just two minutes as Sadio Mane equalised before Andrew Robertson put the Reds ahead before the break.
Arsenal stayed in the game but as they pushed forward for an equaliser, Diogo Jota capitalised on the extra space by wrapping up the victory.
The Gunners have made improvements under Arteta but Keane believes that the defensive trio that started in a back three at Anfield underline how far the club have to go.
‘There’s no getting away from that but he will still want some improvement,’ Keane told Sky Sports.
‘His hands are tied which is a big problem because he still needs a couple more players in.
‘We saw again tonight that defeneivsly – I still think David Luiz, Kieran Tierney and Rob Holding, there’s big question marks over them. Luiz still has that mistake in him’.
Arsenal have submitted two bids for Lyon playmaker Houssem Aouar but neither bid came close to the Ligue 1 club’s valuation of the midfielder.
Atletico Madrid ace Thomas Partey remains a priority but the likes of Matteo Guendouzi and Lucas Torreira before activating a £45m release clause in the Ghanaian’s contract.