Martin O’Neill has resigned as manager of Aston Villa just days before the 2010-11 Premier League season is set to begin. Kevin MacDonald, the reserve team manager, takes over as caretaker manager and will prepare the team for the opening Premier League game of the season against West Ham on Saturday.

No reason was given by O’Neill or Aston Villa for his departure. However, it’s believed that O’Neill has been unhappy at Aston Villa’s transfer policy for quite some time and that he was upset that he hasn’t received the transfer funds he needed this summer to mount a serious challenge to break into the top four in England. At the same time, O’Neill must have been disillusioned by Villa’s selling policy. James Milner is on the verge of a massive transfer fee to Manchester City. And in the past, Gareth Barry left Villa Park to join City also.

O’Neill’s dissatisfaction with Aston Villa owner Randy Lerner’s reluctance to inject more money into the transfer kitty is going to significantly impact Villa’s Premier League campaign, I believe. Here is a proven manager who has done extremely well by turning Villa into a serious team in the Premier League. The club has momentum. While there are plenty of other managers out there who would love to step into Martin O’Neill’s shoes, Villa is going to have a difficult time finding someone who can improve the club’s performance. O’Neill is the type of rare man-management gaffer who takes players and turns them into much-improved athletes. Ashley Young is just one recent example. As far as managers who could replace O’Neill, it’s going to be a difficult time finding someone at such short notice. Sven Goran-Eriksson is the likely candidate. But other than that, who else could do the job as well as O’Neill?

The other question is where does Martin O’Neill go from here? He’s been successful as managers of Aston Villa, Celtic, Leicester City and other clubs. I wouldn’t be surprised if he took a break from the game for a few months and went back into doing punditry on a more regular basis. He may sit out the management game to see who will be the first manager casualty during the 2010-11 Premier League season. Or he could return to Celtic if Neil Lennon doesn’t do well in Glasgow.

According to UK bookies, the leading contenders for O’Neill’s job as the usual suspects: Slaven Bilic, Alan Curbishley, Dave Jones, ad infinitum.