David Moyes throws out the nice guy act and targets an overhaul of his Manchester United squad

Having had a few months to get his feet under the table, David Moyes has evaluated his squad and there's no more Mr Nice Guy

Disappointing performances from his squad have driven Moyes to plan a major overhaul his playing staff

After seven months of playing Mr Nice Guy at Manchester United, David Moyes has decided it is time to be Mr Nasty.

When Moyes first succeeded Sir Alex Ferguson, deference formed the backdrop to everything he said as he settled in to his new surroundings and the challenge of following arguably the most successful manager of all-time.

Moyes, having not won a trophy despite an impressive managerial career at Preston and Everton that earned him his chance at United, paid due respect to the honours accrued by the stellar dressing-room he inherited from Sir Alex Ferguson.

There was no other way he could play it at the start, arriving at a club where the players had more impressive CVs than him and where he would have to prove that Ferguson was right to hand-pick him as his successor.

United's poor start to the season fostered the impression of a squad not fully behind Moyes and his methods, with the reigning Premier League champions struggling to even make the top four and the coveted Champions League spots.

But the club record £37.1million capture of Juan Mata from Chelsea further endorsed Moyes's status as the man to lead United long-term, despite their troubled season, and the 50-year-old felt suitably emboldened by the signing to issue a brutal warning to his under-performing players.

Having already shipped out Anderson, Fabio and Wilfried Zaha this month, Moyes left his squad in no doubt that he will no longer accept mediocrity from the same group of players that won the title by a margin of 11 points last season.

"I'm not going to accept it," said Moyes. "I'm disappointed we're not in a much stronger position. I'm disappointed with how we have played.

"I ultimately take the wrap for that. But what I will do is make it right. I'm going to get better players in.

"I've given every player the opportunity to play and show what they can do. The players have to perform.

"If they want to be here and making sure they have a jersey, they have to show it in the games."

Few of United's players could claim to have played with enough distinction this season to escape Moyes's ire. Even though he inherited the champions, Moyes knew a considerable revamp of the United squad was needed, their wretched form this season serving to underline that view.

Of the current squad, only a select few have impressed Moyes - the likes of Wayne Rooney, Robin van Persie - when fit - Adnan Januzaj, David De Gea, Michael Carrick, Phil Jones and Jonny Evans - and can be assured their status is safe for the  time being.

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Impressed the boss: Young winger Adnan Januzaj

With Rio Ferdinand, Patrice Evra and Alex Buttner set to leave at the end of the season, Nemanja Vidic's future in the balance and Ryan Giggs likely to retire, there are also question marks over Rafael, Chris Smalling, Ashley Young, Tom Cleverley, Shinji Kagawa and Nani, as Moyes looks to build his own lasting squad.

Of course, Moyes cannot strip his entire squad of its personnel, and the change he presides over must be gradual, but his warning , which came on the eve of tonight's Premier League encounter with Cardiff at Old Trafford, suggested there will be a major shake-up at United this summer.

Moyes said Mata's arrival was just the start of his long-term strategy to re-establish United as the country's dominant domestic side and a major force in Europe , as they were for two decades under the peerless Ferguson.

Ferguson may have been responsible for United's remarkable period of sustained success, but he also left Moyes a squad in dire need of attention, something his successor is poised to address, now the honeymoon period is over for those who have failed to deliver for him.

They have been given a chance by Moyes but too many of them have fallen short of the standard expected at a club of United's standing and, as such, will be on their way in the summer. As the signing of Mata has proved, United do not stand for mediocrity for long.