Those supporters were up in arms when the decision came to get rid of the Australian but in the end there were issues at the club that meant Cahill’s achievements were somewhat overshadowed.
Aaron Mooy is not at that stage with Shanghai SIPG but there are reasons to be concerned.
Finishing fourth in the Chinese Super League was not part of the plan and is a disappointment for an ambitious club that has the most expensive foreign contingent in Asian football - Hulk, Oscar and Marko Arnautovic cost around a quarter of a billion dollars.
Bringing in an established English Premier League midfielder such as Mooy was also not exactly cheap.
That the 2018 Chinese champions didn’t manage to book a place in the 2021 AFC Champions League is another huge disappointment.
It means that the only pathway to Asia is to win the FA Cup (though with the first team in Qatar for the 2020 AFC Champions League, it will be far from easy for the second team to get through the rounds - though if one of Guangzhou Evergrande, Beijing Guoan and Jiangsu Suning, the teams that finished above Shanghai in the league, win the cup then Shanghai can squeeze in).
After his surprise transfer from Brighton and Hove Albion in August, Mooy started off well with a goal on his debut and has been steady rather than spectacular in midfield since.
He has not, so far at least, been a notable improvement on Odil Ahmedov, the player he replaced, though it should be pointed out that he has been playing for just two months and ten games in total.
Coach Vitor Pereria, now three years in the job which is a decent spell for a foreign coach in China, is under pressure after the major investment in the team has not brought any silverware.
Failure in the 2020 AFC Champions League that resumes next week against Sydney FC could see the Portuguese boss out of a job.
It's fair to say then that Mooy has come into a team that has plenty of issues.
Shanghai are looking a shadow of the side that won the title two years ago.
They have become more defensive, more focused on counter-attack, less fluid and more direct.
More worrying is team spirit with the coach complaining in recent weeks that it is not what it should be - never a good sign - with speculation focusing on Hulk and Arnautovic.
This season has been tough as all Chinese Super League teams have been confined to hotels since July.
Players, staff and officials are allowed out only for training and games and are immediately returned.
Being stuck in hotels with team-mates for months can turn cracks into something bigger.
Hulk is 34 and understandably not the force he was. The Brazilian has been a star in China since arriving in 2016 though this season he has failed to reach such standards consistently.
There have been theories that this is because he is leaving at the end of the year - he said goodbye to fans earlier this week on social media - and that he is concerned about picking up an injury.
Regardless, at his age, it is not a surprise that Hulk is slowing down and lacks a little of the raw power and energy that made him such a force. It has also left SIPG a little predictable going forward.
It also seems that the boss is not a big fan of Arnautovic who arrived in 2019 from West Ham.
The Austrian scored seven times in the first half of the season but his performances dropped sharply in the second half and he has failed to add to his tally.
Arnautovic could well be heading out of the club, if there is another willing to pay a similar salary and there are going to be plenty of other departures.
Of course, winning the AFC Champions League is a chance for success but it could easily go the other way.
A long flight and the prospect of another month or so stuck in a Qatar hotel may not have Shanghai in the best frame of mind as they prepare to take on Sydney FC next Thursday.
The continental tournament does at least give Mooy a chance to really carve out his place in the team.
If he can inspire Shanghai to success in Asia then it would be a perfect way for the club to end a disappointing season and help to ensure that whatever happens - and there are sure to be many changes at one of China’s biggest clubs before the start of next season - Mooy's time in Shanghai is longer than Cahill's.
