Pardew just had to go. He had decent players like Tevez, Mascherano, Reo Coker and Ferdinand (apparently, I've never seen anything special from him but others rave about him) all under performing. They have a team of potential if they can hold on to them.
The excuses had wore thin and they worst vs Bolton than before.
They are only four games out of the European places in an open season but with Pardew they were just getting worse. What would happen IF they got SWP and he turned out to be the same as the others who are under performing? They need someone capable of getting the best out of this squad and any future players who have quality. The timing was perfect.
The loss to Bolton was abject and the game at Man U would be expected to be a loss. So the board have to weeks if they believe they need a quick replacement. Personally, I don't think they have the full squad to get into Europe but if they believe they have they needed to act before that possibility was a distant memory.