When he took the job there was little hope he would do much better than his predecessors.
The top trend in Italy during his unveiling read #PioliOut and the general feeling was of being underwhelmed and frustrated that the club didn't attract an A-list name.
And yet fast-forward to this weekend and Pioli is preparing to lead Milan out for the final game of the 2019-20 season having completely transformed the mood around a club blighted by disappointment.
That form has been rewarded with a new contract amid talk Ralf Ragnick was waiting in the wings. While there was some truth to Milanese interest in him, Pioli rightly has the club's full support and has extended his deal to June 2022.
Along with the backing of Ivan Gazidis off the pitch and the buy-in from Zlatan Ibrahimovic on it, Pioli is now looking up rather than down. For the first time in a long while, the dark clouds hovering over the San Siro have parted for the sun.
One of Pioli's biggest successes has been his coaching, particularly with such a young squad to inherit - aside from Ibrahimovic.
But there is more to it than just hard work at the club's Milanello training facility. Sportsmail looks at how it proved eighth time lucky for Milan and their supporters.
Pioli has always done well at other clubs but to the point where it has never been good enough to win honours. He has had spells at Lazio, Fiorentina and Inter but didn't win a trophy with any of them.
Milan's call came when it soon became apparent that the Marco Giampaolo experiment was going wrong fast. Slumped in 13th, a dressing room devoid of confidence and three points separating them and the relegation zone, the club needed a new voice, a fresh face and Pioli brought that.
His man-management skills are among his most impressive traits and they have been shown best at the San Siro this season with Ante Rebic and Alexis Saelemaekers.
Rebic was anonymous and his impact limited in the brief tenure of Giampaolo but under Pioli he is a jewel in this current Milan side. Saelemaekers, 21, is developing into a cornerstone piece for Milan to build around for the future, a real diamond.
Starting first with Rebic, it all started to change for him in the Italian Cup, with the encouragement of Pioli, when Milan beat SPAL 3-0 in the round of 16. Rebic played in a front two alongside Krzysztof Piatek - no longer at the club - and since that game he has netted all 11 of his Serie A goals this season.
Prior to that he didn't have a league goal or an assist to his name in a Milan shirt.
Then take Belgian star Saelemaekers. He has become Milan's new talisman: Pioli relies on the Belgian Under 21 leader due to his versatility, in every defensive role, as a full-back, and in midfield.
Drawing similarities to Gennaro Gattuso, now Napoli boss, the Belgian has boundless energy and also has that scrappy nature which has helped remove Milan's soft underbelly which looked so expose to start this campaign.
According to Sky Sports Italia, keeping hold of Pioli was key to the club retaining legend Paolo Maldini behind the scenes.
Maldini and colleague Frederic Massara would have departed had Rangick arrived, it has been widely reported.
The management team of Gazidis, Maldini and Massara communicated the confirmation of Pioli staying inside the dressing room and received a round of applause from everyone.
Pioli has brought serenity within the Milanese environment and has selected players not based on status or their celebrity of their surname but a side built on good principles and good foundations.
Maldini will have been hurt with seeing how this once great club have fallen by the wayside but with Pioli given his backing, things are looking up for 2020-21.
It is amazing how winning changes the entire complexion of a situation, particularly at a football club.
With Milan, along with Atalanta, the form side in Italy in 2020, the notion of pushing Pioli aside for Rangnick only became more and more unpalatable - and that extended to the dressing room.
In an interview for 'Sport Week' Ibrahimovic said that 'you don't know Rangnick' when asked about the Leipzig chief's credentials.
Ibrahimovic, even at 38, is as crucial off the pitch as he is on it and many look to him in the squad. Upsetting the Swede and pushing him out the door with Pioli was risking a mutiny.
According to Sky Sport Italia, Milan also gave up on Rangnick because of the €8m fee - considered excessive in Milan - it would have taken to free him from his contract with Leipzig.
The German coach would also have occupied three different roles with a salary higher than that of Pioli and would have played a leading role in every key role of the club.
The old adage of if it is not broke, don't fix it, came to mind when the issue of whether Pioli or Rangnick would take them forward. In the end, Pioli's case was watertight.
Former England boss Fabio Capello has always been against the idea of appointing Rangnick as he explained in an interview with Radio Anch'io sport: 'Milan would lose a year if they changed coach.
'I am convinced that it is better to continue with Pioli. He has managed to give a group mentality that was not seen before. Indeed, for years this management of the locker room has not been seen.'
The blessing of Capello, one of the most successful coaches in the history of the Rossoneri, is confirmation of the feeling around Pioli right now.
Derided on arrival and mocked across social media, Pioli stuck to his beliefs and now has the backing of legends. While there is still work to do, Milan's renaissance - after years in the wilderness - is up and running.
