I think that Mourinho is still a good coach but he definitely lost his aura of being the special one, after his last few stations of a coach were not that successful. His biggest achievement was definitely the champions league title win with Porto in 2004 but his first time with chelsea was also pretty successful even though they did not manage to win the champions league title then.
I have to say though, that the teams of mourinho never played really attractive football but he really managed to make the entire team fight for each other. So he really is a great motivator or at least he was, but i am not sure if this is enough anymore.
I understand they are in search for a new coach,but that doesn't mean they will higher an average coach.Morinho is now seen as an average coach,he has nothing unique again.They should look for other options,some one who can build the team again,and turn things around at the club.