Arsène Wenger has pledged to mount a rigorous examination of Arsenal's shortcomings when the season is over and may be dismayed to discover that many of the club's fans have begun to do so already. For all the manager's defiance in defeat in the Champions League quarter-finals, the chances of his team recovering to win the Barclays Premier League title are remote, with the strong probability that they will finish the season empty-handed for the third successive year.

Arsenal's collapse has not been as spectacular as last season, when after failing to contest the championship they crashed out of the Carling Cup, the FA Cup and the Champions League in ten days, but it has been dramatic, with three matches against Liverpool in seven days effectively putting an end to their challenge in the Premier League and in Europe. Wenger's reaction to the defeat at Anfield on Tuesday was to blame the referee, but there are more deep-seated reasons for his team's implosion. Where did it all go wrong?

Timing

Few people recall that Manchester United failed to win any of their first three Premier League matches of the season because they are finishing it strongly, whereas Arsenal have done the reverse. In the past two months their results have been dire, with only two wins from their past 12 matches in all competitions, allowing United to turn a six-point deficit into a six-point lead in six weeks. In retrospect, the tipping point in Arsenal's season may have been that 4-0 FA Cup fifth-round defeat at Old Trafford, since when they have managed to win away to AC Milan and Bolton Wanderers, thanks to late goals.

Squad

Such a sudden loss of momentum has put the focus on the size of the Arsenal squad. Wenger chose not to strengthen in January, arguing that there were no players of sufficient quality available, although, given that Robin van Persie had been carrying injuries all season and the shortcomings of Philippe Senderos, the failure to sign a striker and a centre back appears a costly mistake. A bigger one may have been allowing Lassana Diarra to join Portsmouth because the 23-year-old looks to be maturing into a midfield player of quality.

Mental frailties

Arsenal have toughened up from the days when any trip north was a wasted journey, winning away to Blackburn Rovers and Bolton this season, although certain weaknesses remain. Much of it is down to the inexperience that triggered their downfall at Anfield, as well as the temperamental nature of several key players, such as William Gallas and Emmanuel Eboué. Wenger's stubborn refusal to admit mistakes may not help them to learn the error of their ways, either.

Style of play

By scoring six of their past nine goals from set-pieces, Arsenal have proved that they are no longer one-dimensional, although they have an infuriating tendency to overcomplicate. The directness and tactical flexibility of Rafael Benítez would not go amiss occasionally, although those calling for an overhaul should consider whether they would be happy watching Liverpool every week.

Have Arsenal underachieved?

Wenger claims that his team have made progress by staying in contention far longer than last season, but having come so far, there is bound to be disappointment. The Frenchman has repeatedly fallen back on the predictions that Arsenal were expected to struggle this season, so it would be disingenuous of him to claim otherwise. While a talented team are still improving, they must win trophies soon or risk wasting their potential.

Can Wenger be blamed?

As with many great leaders, his biggest strength - a commitment to attacking football played by young athletes assembled without breaking the bank - is also his biggest weakness. Wenger is unwilling to compromise in either regard, which may undermine his search for silverware but has made Arsenal the most entertaining side in Britain for several seasons. Most Arsenal fans would agree that the sacrifice is worth it.