The Portuguese arrived back at Stamford Bridge last summer after a six-year absence, and slowly but surely, the Blues have regained the aura that made the club so formidable during his first spell in charge.
What was so special about that Mourinho team of a decade ago was its ruthless pursuit of glory. It was a win-at-all-costs mentality that brought with it back-to-back Premier League titles, two League Cups and the FA Cup.
Chelsea would steamroll their opponent, suffocating it to within an inch of its being. The Blues were a juggernaut that threatened to dominate the English game for a generation, in much the same way Sir Alex Ferguson's Manchester United did.
Mourinho's Chelsea were a fine example of physical and tactical prowess, rightly winning plaudits from some. That said, for football purists, the Blues resembled an anti-football of sorts.
Where Chelsea fans saw beauty in the club's trophy cabinet bulging like never before, neutrals lamented the style with which the Blues acquired their status.
So too, it seemed did Roman Abramovich.
Success was welcome, but Chelsea's Russian owner wanted to do things with a little more panache. When Mourinho departed Stamford Bridge, so began the quest to replicate the Barcelona model.
In came players such as Deco, who would be followed in later years by the likes of Juan Mata, Eden Hazard, Oscar and a host of other diminutive types with a view to playing Chelsea's own interpretation of tiki-taka.
Even Chelsea's youth teams were employing players of this ilk as Abramovich and his technical director—at first Frank Arnesen and then current incumbent, Michael Emenalo—endeavored to force through a new culture in West London.
Rome, or in this instance, Barcelona, wasn't built in a day, as we know. And Abramovich has learned that fact much to the detriment of Chelsea's success.
Trophies have continued to make their way to West London, but not at the rate they should have. They've trickled rather than flowed, and as for competing for the title, until now, they have been nothing more than also-rans.
The special teams we have seen coming out of the Nou Camp in recent seasons have taken decades to build. They have been influenced by a culture that is ingrained throughout Barcelona.
There's a long-established ethos in Catalonia that is eminent in their team, and it takes much more than the billions of an oil magnate to establish it.
Yet just as Barcelona must be applauded for their style, so too must the teams Mourinho has built as Chelsea manager.
Although their qualities may differ from Barca's, they are just as endearing.
Chelsea have long been among the leading clubs in English football—not finishing outside of the top six since 1997, long before Abramovich came on the scene—yet their new ownership in 2003 propelled them to sit among Europe's elite.
They certainly ruffled the feathers of the more traditional powerhouses across the continent, and call it a case of the jitters, the quest to win over neutrals smacked of the club looking for acceptance from their peers.
Mourinho is a man who craves acceptance merely from his own, however.
Indeed, the Portuguese isn't concerned about what outsiders think. It's about Chelsea for him and what works at Stamford Bridge.
In attempting to change their style and with it, the club's identity, Chelsea became a soft touch, almost. They may have challenged for titles, but one further Premier League success in the eight years since 2006 tells it's own story.
Now that Mourinho is back, that's changing. We're already seeing it this season.
Chelsea's title challenge in 2014 is going down to the wire, while they are among the favorites for the Champions League with a realistic chance at repeating their 2012 success.
There is a renewed optimism, and it's been brought on by the manager.
Mourinho's Chelsea are still developing, and much like times past, they are adopting that ruthless streak that once saw them feared across Europe. And he's doing it by being pragmatic, playing to Chelsea's strengths, not that of others.
Against Arsenal last week, it was counter-attack football, utilizing Hazard and Andre Schurrle on the flanks, that proved to be the Gunners' downfall as they crashed to a 6-0 thumping.
Chelsea beat Arsene Wenger's men by doing things their way, not any other.
For some time it's been the opposite. It's been as though Chelsea have tried to fit in. Not anymore.
It's been refined since his previous stint, and now Mourinho's way is returning, much to Chelsea's benefit. That can only mean one thing.
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.