In fact, Chelsea haven't exactly been at their best at all. Yet here they are among the leading pack, six months after Mourinho's return and looking stronger with each week that passes.
So many things have changed in the years since the Portuguese departed West London in 2007. There are a few familiar faces from his first stint, although this squad is very much different to one he inherited from Claudio Ranieri.
It's a squad that is much younger in years and experience, but that hasn't prevented the Blues manager from leaving his mark. It may have taken time, yet that bulldog spirit Mourinho's teams are so famous for is beginning to rear its head.
Indeed, in 90 minutes against Hull at the KC Stadium last Saturday, Chelsea played out their entire season up to now. And judging how that game panned out, it could yet prove to be a crystal ball for their fortunes in 2014.
A less-than-satisfactory first half saw Chelsea grind the Tigers down after the interval. They had gifted them a few opportunities early on in the game, but with the score goalless at half time, Steve Bruce's side would be left to rue their missed chances.
With Eden Hazard leading them, the Blues chipped away at Hull's rearguard before eventually getting their reward—Hazard himself opening the scoring just before the hour, followed by a Fernando Torres strike on 86 minutes to kill off the opposition.
If that first half at Hull represented the first six months of Mourinho's reign, what followed in the second would have made Chelsea's rivals sit up and take a little more notice of them if they hadn't already.
Chelsea hounded Hull, wearing them down, and in the wider picture of Premier League dominance this season, it could be the same for Arsenal and City come May.
NBC Sports' Arlo White noted that much in a recent Google Hangout on Bleacher Report.
"Chelsea's grind is back," he said. And the commentator isn't far off the mark.
What we had seen from Chelsea in the beginning stages of 2013-14 was a team flattering to deceive. There had been talk of an emphasis on attack, a tiki-taka-esque approach to appease Roman Abramovich's desire for free-flowing football at Stamford Bridge.
It didn't quite work, though.
We're still seeing it in stages of matches, although the Blues have added a bit of steel to their repertoire.
Out have gone the defensive vulnerabilities, replaced by a team that looks solid and ready to be unrelenting in their pursuit to grind down the opposition.
"It is one of the easiest things in football, it is not difficult. You organize your team from the defensive idea. You don’t give freedom to your players to express themselves. The dynamic of the team is defensive in what you do. You recover the ball and try to punish your opponent."
Things haven't been as drastic as that, yet it cannot be ignored that Chelsea have adopted a more pragmatic approach since.
Purists who may feel disenchanted will have little to support their desires for Mourinho to maintain his earlier brief of exciting fans with an attacking brand of football.
Nothing gets supporters on their feet like a victory, and Chelsea are getting them aplenty right now.
Since that Sunderland loss, the Blues have won five of their six matches—drawing with Arsenal at Emirates Stadium—and have conceded just one goal.
Depending on the mindset of the fan, the change in the club's style of play will be viewed two ways—evolution or a significant step back. Whatever the conclusion, there can be little argument as to the positive impact it has had on the campaign, however.
Mourinho is showing his craft as a tactician, as a world-class coach. His team's development continues, and unlike Manchester United, who themselves are undergoing a similar transition, Chelsea have a very real chance of finishing the campaign as champions.
Nemanja Matic was signed on Jan. 15, adding some much-needed defensive nous to the Blues midfield. The Serbian's return to Stamford Bridge is an indicator that the pieces to Mourinho's Chelsea jigsaw are beginning to fall into place, and after six months back in the hot seat, even he wouldn't have expected it to happen so soon.
Garry Hayes is Bleacher Report's lead Chelsea correspondent and will be following the club from a London base throughout the 2013-14 season. Follow him on Twitter here @garryhayes.