Title Contenders or Title Pretenders?

Arsenal have been labelled title pretenders for the past few seasons. Sometimes, having a good start to the season and breaking at the later stages of the competition (between Dec. & Feb)

Now they have played themselves to the summit of the table with 5 wins in 6 matches and would be hoping to be there come end of the season.

Undoubtedly, Ozil's signing has been good for them going forward with the German racking up 3 assists in as many games in the EPL but the Gunners are yet to find the balance at the back, keeping only 3 clean sheets in 10 matches in all competitions this season (2 in the UCL play-offs and 1 in the EPL against Spurs). The last time they kept a clean sheet was 6 matches ago.

For Arsenal to be regarded as genuine title contenders, they have to play their leaky defence and as the saying goes "a good attack would only win you matches but a good defence would win you the league".

Was Mourinho right when he regarded Arsenal as title contenders?