Arsene Wenger's side are eight points behind Premier League leaders Leicester

Arsenal manager Arsene Wenger has used the FA Cup as a safety net for the last two seasons - final victories against Hull City and Aston Villa bringing the success that has eluded him elsewhere for so long.

Now, he cannot rely on the famous old competition to protect him - or his failure to win the Premier League since 2003-04 - after Watford's shock 2-1 quarter-final win at Emirates Stadium.

So no FA Cup, as good as out of the Champions League as Arsenal attempt to overturn a 2-0 deficit against holders Barcelona in the Nou Camp on Wednesday, and eight points behind Premier League leaders Leicester City after two losses and a draw in their last three league games.

The 66-year-old is a towering figure in Arsenal's history - but if the Gunners finish this season empty-handed it must be time for Wenger to consider relinquishing control of the club he has served with such distinction since September 1996.

So why should the end of Wenger's era be on the agenda?

Arsenal's lack of success?

Arsene Wenger has won nine major trophies at Arsenal but they have not won the league for 11 years

No Arsenal fan - even Wenger's fiercest detractors - would wish to see a wonderful career peter out to the soundtrack of growing criticism after bringing three titles, which also included two doubles with the FA Cup, and six FA Cup triumphs in all.

There comes a time, however, when any manager's recent record must be subjected to close scrutiny, irrespective of the past. It is not a vendetta or a personal campaign against Wenger, simply an examination of unflattering facts.

It is the law, the reality, of football management.

And if Arsenal do not win the title this season, a campaign they have almost been waiting for in many respects, the time would be right to hand over power because there are no signs that Wenger is close to recreating his successes of the past.

Arsenal dominated possession at the Emirates and had 20 shots in total, compared to Watford's seven

If he fails again, Wenger will have faltered with Arsenal's rivals all stumbling around them. Chelsea have imploded, Manchester City have been indifferent and Manchester United have been off the radar.

It would be a desperate reflection on Wenger and his team if they fail to take advantage of that collection of circumstances.

Since that last title, on the back of 38 games unbeaten, Wenger has only finished second once, in the following season. There have been six fourth-placed finishes and four seasons in third. Arsenal have rarely threatened to actually win the title again.

And if they go out to Barcelona, it will be their sixth successive Champions League exit at the last 16 stage.

If history repeats itself this season, then it must be the end of the old "Arsene knows" and "In Arsene we trust" mantras, and change must be considered. Wenger cannot be immune from the normal measures of success and failure.

Arsene Wenger - Arsenal career stats Competition Games Wins Draws Losses For Against Win % Premier League 743 429 183 131 1391 706 57.74 Champions League 182 92 40 50 290 189 50.54 FA Cup 102 67 22 13 194 81 65.69 League Cup 64 36 8 20 132 88 56.25 Uefa Cup 11 6 3 2 22 11 54.55 Community Shield 8 6 1 1 15 5 75.00

Toxic atmosphere at Arsenal

Any regular visitor to Emirates Stadium will sense the growing frustration and fury among Arsenal fans as their team falls short - an understandable emotion they rightly feel at this huge club.

There were reports of Arsenal supporters confronting each other after the FA Cup loss while a tetchy Wenger described criticism (justified given Arsenal's recent record) as "a farce".

Arsenal fans brandished a prominent banner at the 4-0 FA Cup fifth round replay win at Hull City bearing the words: "Arsene. Thanks for the memories but it's time to say goodbye."

The air can only be cleared by a trophy and will become more polluted by criticism should Arsenal, as they so often have under Wenger in recent times, come up short once more. Or it could be cleared by a change of manager.

There is growing unrest, not helped by Leicester City's rise to the top and north London rivals Tottenham moving into second place, with Wenger inevitably the central figure and the focal point for fans' disappointments.

This, in reality, means winning the Premier League. Surely Wenger's future now largely hinges on that.

Wenger's failure to address weaknesses

Arsenal's flaws remain the same this season as they have for so many of the barren years. Responsibility for that lies with the manager.

Wenger has invested in big signings by bringing in £42.4m Mesut Ozil from Real Madrid and Alexis Sanchez from Barcelona for £32m - but old failings have been left unattended to undermine Arsenal.

Indeed, Arsenal were the only major club in Europe's top five leagues not to sign a single outfield player last summer. Show of faith or flawed gamble? It will be seen as the latter if Arsenal win nothing.

Arsenal have lacked a powerful midfield presence for many years, yet Wenger has failed to address the problem. It has led to a heavy burden of responsibility being placed on Francis Coquelin, with a free transfer in his second spell at the club, Mathieu Flamini, as back-up.

And while Olivier Giroud is a serviceable Premier League striker, he is short of true world-class and once again Wenger has failed to produce. Arsenal have been linked with Luis Suarez, Karim Benzema and Gonzalo Higuain, to no avail.

Wenger's once golden touch in spotting and capturing the best youngsters also seems to have deserted him, with Juventus snapping up the brilliant 22-year-old Argentine Paulo Dybala and Borussia Dortmund's Pierre-Emerick Aubameyang stating he has no interest in moving to north London.

He was on Arsenal's radar when he was at St Etienne but moved to the Bundesliga in 2013.

Wenger bristles at suggestions Arsenal lack natural leaders but their constant failures and mental weakness at pressure points suggest otherwise - as seen against Watford and also when they lost 3-2 to a youthful and injury-hit Manchester United in February.

These problems have been a narrative in Arsenal's failures - and Wenger has not changed the storyline.

Arsenal's board will not escape scrutiny either, but Wenger has never suggested in recent years that he was stopped from spending money. He has simply adopted a frugal approach that has seen the club left behind.

A natural end?

Arsenal have won two FA Cups and two Community Shields in the last two seasons

Sometimes a manager's time simply comes to a conclusion. Twenty years is a lifetime in football and Wenger may well be the last Premier League manager to preside over a dynasty.

And, no matter how fiercely the desire burns to bring back the former glories, a fresh voice is needed - and that time may have finally arrived at Arsenal.

Change is often required to refresh hearts and minds and simply blow away the cobwebs within a club. This is not a criticism of Wenger, simply that a manager's timespan just comes to an end.

Wenger's words praising Arsenal's spirit and attitude have been a constant accompaniment to a lack of silverware and it has been present again during a run of just four wins in 14 games.

It is a familiar sound, but a hollow one after defeats, and maybe it has become too familiar to his players. They do not back up Wenger's words with actions - maybe they now need to hear someone else.

History will remember Wenger as one of British football's greatest managers, but all good things must come to an end and some results and performances in recent weeks have smacked of the last days of his reign.

There is no agenda against Wenger. There is barely anyone who would begrudge him a happy ending at Arsenal.

Football, however, is not always like that.

Who could replace him?

Arsene Wenger is the current longest-serving Premier League manager having taken charge of Arsenal on 1 October 1996

This is now actually the biggest problem facing Arsenal's board after their years of complete loyalty to Wenger. It has meant those who would be a perfect fit for the club have gone elsewhere.

Two of the prime contenders are no longer available. Pep Guardiola, who many believe would have seen Arsenal's location, infrastructure and financial power as his perfect Premier League platform, is joining Manchester City, while Jurgen Klopp is at Liverpool.

Manuel Pellegrini will be available at the end of the season after leaving Manchester City, but is the 62-year-old an upgrade on Wenger?

Jose Mourinho is also available but he seems destined for other parts and is hardly the sort of combustible character Arsenal's board would consider, despite his great success. Forget that.

Exit from FA Cup very sad - Arsene Wenger

Ajax manager Frank de Boer would surely welcome the move. He has no Premier League experience but has great pedigree as a player and has won four Eredivisie titles.

Bayer Leverkusen coach Roger Schmidt is highly rated, while plenty with Arsenal connections might emerge from the pack.

Steve Bould has worked alongside Wenger but has no managerial experience, while others are serving their apprenticeship.

Patrick Vieira appears to have been lost to Manchester City as he now coaches New York City FC, Dennis Bergkamp works with De Boer at Ajax, while Thierry Henry has just completed his Uefa "A" coaching qualifications.

If Wenger leaves he will be a hard act to follow - and a hard man to replace.