The case for the prosecution is gathering momentum while the defense’s Groundhog Day excuses lose credibility with each poor result.

Had anyone suggested last August that Manchester United and Arsenal would miss out on a top-four finish with David Moyes and Arsene Wenger leaving their respective positions, they would have been ridiculed.

Now, particularly with United and Moyes, he has been found guilty by a majority verdict of being a failure who is out of his depth at Old Trafford.

While Moyes inherited a United team which was the defending champion, it was obvious the side Sir Alex Ferguson left needed new blood. Moyes signed only one player last summer, spending £27 million on his former Everton player Marouane Fellaini, who has made more of an impact with his elbows than his feet. More than one new arrival was needed and Moyes spent too much time chasing players such as Cesc Fabregas, who was never going to leave Barcelona, leaving United without the injection of fresh talent that was so obviously required.

Jose Mourinho must be laughing to have sold Chelsea’s double player of the year Juan Mata to United in January for £40 million because under Moyes the Spaniard looks more like a £4 million capture.

Moyes is playing Mata as a winger, a role he is clearly not suited to and, like Fellaini, he has yet to score for United.

To go from being champions to seventh, playing wretched football is a dubious achievement, United becoming the first reigning top flight champion in 51 years to lose six or more of its first 15 home matches since Ipswich Town.

When some of the Old Trafford faithful boo Ferguson because he chose Moyes as his successor, it is a clear indication of the frustration, anger and helplessness felt by the fans. As one of the biggest clubs in the world, it is astonishing United did not draw up a short list of candidates; instead it allowed Ferguson to name and effectively appoint the man to succeed him. In no other industry would the top job be given to an unqualified candidate sourced from a pool of one.

Many felt Moyes was not the right man for the job when he was appointed as manager last July, an underwhelming choice who, nevertheless, has had fantastic support from United supporters and, to a large extent, the media. However, what Moyes has done to United, and the way he has done it, that unwavering support is collapsing to the point where it has almost disappeared while the press has run out of reasons to be understanding.

One good night at Old Trafford, defeating an Olympiakos side which United should be beating in its sleep, was required only because of a first leg 2-0 defeat in a performance so inept it probably ranks as its worst ever in Europe. The Athens debacle was not a one-off because too many United displays under Moyes have been gutless, heartless, ponderous, predictable and passionless.

There is more than Ferguson’s departure behind United’s current position. From winning the title by 11 points it now trails Chelsea by 18 points, its chances of even a Europa League place questionable. United has 51 points compared with 74 at the same time last year, a turnaround of 23 points. Previously, United has never had fewer than 60 at this stage, another ignominious record for Moyes.

A defiant Sir Bobby Charlton said: “(I) am absolutely sure we picked the right man,” but it is an opinion that lacks credibility and cannot be backed up by a reasonable argument. It must hurt Ferguson to see his team, his club and all his hard work undone in eight months.

Replacing Moyes, who was given a six-year contract, after one season would be an embarrassing, expensive admission of failure for not just Ferguson, but also the Glazers, who must be wondering if they can trust a man who has paid over the odds for two players yet to look even adequate with a summer rebuilding job.

Any club, even United, not in the Champions League will struggle to attract the top players this summer while Moyes is a manager who is barely known in Europe. He was an excellent manager at Everton, but the growing feeling is that this was his limit, that he does not have the tactical know-how, confidence or strength of character to move up to the top level demanded at United. It is uncomfortable to see a decent man like Moyes struggling and there has been little evidence to have confidence that Charlton’s opinion in him is justified.

Moyes’ post-match press conferences have taken on a familiar tone, with almost just the name of the opposition changed among the regular excuses for inadequate performances. A club which has had nothing but success over the past 25 years is now surrounded by negativity and even the most loyal United fans are running out of reasons to stay behind Moyes.

Arsenal, meanwhile, is losing ground to Everton in the race for fourth place after the 6-0 beating by Chelsea and 2-2 home draw against Swansea.

Wenger, whose current deal ends this summer, has yet to sign a new contract and the number of Arsenal fans who would like to see a new man at the helm is increasing significantly. The Gunners remain favorites to win the F.A. Cup but Wenger is unlikely to change his style of management, which shows misplaced loyalty to his players, believing them to be better than they are. Arsenal struggles against the Premier League’s top guns and the voices in favor of a change of manager are getting louder, though a personal view is that Wenger will sign a new two-year contract.

Should either or both of the English heavyweights be looking for new managers, Frank de Boer, who has led Ajax to three consecutive titles, and Jurgen Klopp, who has guided Borussia Dortmund to two Bundlesliga crowns, are sure to be on any wanted list. Holland coach Louis van Gaal has made no secret that he would like to work in the Premier League after the World Cup, but Tottenham seems the more likely destination for the Dutchman.

Christopher Davies was a longtime Premier League correspondent for the London Daily Telegraph.