City were desperately unlucky not to beat Everton last time out, denied only by an outstanding performance from Toffees 'keeper Tim Howard and some poor refereeing.
Despite the draw Manuel Pellegrini's side are still just three points off the top of the league.
They are also in the last 16 of the Champions League, the semi-final of the Capital One League Cup and through to the fourth round of the FA Cup with silverware still a very realistic prospect.
But BBC pundit Shearer, who scored 313 goals in 622 career games for club and country, wrote in his latest blog on Coral that the inconsistency of one of their key players, Yaya Toure, casts doubts over City's title credentials.
"Yaya Toure has come in for some criticism this season for his performances," Shearer wrote on Coral.
"What I will say about Yaya is he has an incredibly amount of ability but we should be seeing it more often.
"We see flashes of it but we are not seeing it on a long run.
"That will be the most frustrating thing for Manchester City and their fans.
"That has been one of the problems for the team, and that lack of consistency could ultimately cost them the title."
Shearer criticism unjustified
Toure is regarded as one of the top midfielders in the world and therefore has set high expectations for his performances.
But Shearer's criticism is harsh given that the Ivory Coast legend has five goals from 19 league games so far this season and numerous assists.
That's two more goals than Arsenal midfielder Mesut Ozil, widely regarded as one of the players of the season so far.
Shearer is perhaps right in that City should be more dominant domestically thanks to their vast riches and expensively assembled squad.
But they have suffered with injuries to key players like captain Vincent Kompany and strike star Sergio Aguero all season long and Pellegrini often struggles to field the same team in consecutive games.
It is not the first time Shearer has questioned City's title prospects either.
Last week the Newcastle United legend questioned the team's mentality in this most open of Premier League seasons.