After selling star midfielders Samir Nasri and Cesc Fabregas to Manchester City and Barcelona respectively, the North London outfit experienced one of their worst starts to a season in their history.
Along with a stuttering start to the campaign, they also succumbed to a 2-1 loss against fierce rivals Tottenham Hotspur earlier in the month, which saw them sit in an uncomfortable 15th place with only seven points.
With a lack of investment injected into the squad after a summer of sales, many were questioning Wenger’s ability to win trophies at Emirates Stadium after six seasons without silverware.
Despite the negativity surrounding the club, their form has increased since the loss to Tottenham, and former Aston Villa manager O’Leary has hailed the Frenchman’s reign at Arsenal and believes they can improve.
“Arsene Wenger is a fantastic manager,” he told Yahoo!
“When I left Arsenal we were a big club but Arsene Wenger has moved them onto another level.
"They’ve even built a bigger stadium because they outgrew the old stadium. He has been amazing in that way.
"Everybody knows they play great football but they haven't won anything in recent years which people keep referring to; they will know they need to put that right.
"They have started to leak more goals but I am sure they will be working to rectify that as well.”
Irishman O’Leary, who went on to make more than 500 appearances for the three-time Premier League winners, also believes that the signing of German centre-back Per Mertesacker will tighten up their defence.
“They can play great football, but consistently they have conceded too many goals and shown frailties in defence,” he added.
“When they are one up, they might be dominating the game but you often feel the other team has got a great chance of equalising.
"Bringing Mertesacker in will give them a bit more height which will help when they concede free-kicks and corners.”
For more insight from David O’Leary and other leading managers, plus exclusive Barclays Premier League highlights, go to www.yahoo.co.uk/sport
'Will Cristiano Ronaldo and Neymar extend their contracts in Saudi Arabia? We play a facilitating job, but it’s down to the players and the clubs to decide' Saudi Pro League chief reveals how talks will work for out-of-contract duo
Nations League: Who are the ITV commentators and pundits for England vs Republic of Ireland?
