Last Thursday, Stiliyan Petrov found himself treading familiar ground. Yet, as Stuttgart visited, there was a distinct unease lingering over Celtic Park.

“It’s renowned for its atmosphere,” the Bulgarian remarked. “The passionate fans, the singing, the sheer emotion and enthusiasm. I’ve never seen Celtic Park overpowered by the noise of rival supporters. Right now, it feels oddly different.”

The subdued ambiance can partly be attributed to the ongoing suspension of the Green Brigade. However, the lack of volume from the crowd reflects a growing frustration among fans who feel disheartened by recent events both on the pitch and within the club.

“Everything has been off since the season began,” Petrov continued. “It seemed bound to happen. The club has grown too complacent over the past few years.”

“By this time of the year, Celtic typically enjoys a secure position. But now, they’re struggling, likely due to poor choices in the last two transfer windows. Not backing the managers adequately and frequent managerial changes have taken their toll.”

O’Neill looks crestfallen after his Celtic team were easily beaten by Stuttgart last week

Sebastian Tounetki can only look on as Stuttgart celebrate victory at a flat Celtic Park

The Parkhead side then followed up that Euro defeat with a Premiership loss at home to Hibs

Although the league title and Scottish Cup remain within reach, it’s hard to imagine the current state of affairs continuing unchanged.

Celtic have the look of an analogue club who are now hopelessly ill-suited to operating in a digital world. There’s no vision or a grand plan. Too few people in senior roles are there on merit.

‘Maybe Celtic have to restructure,’ said former midfielder Petrov. ‘I think the club have been outdated. In modern clubs, the way they’re working, the sporting directors and technical directors are navigating and taking action. They are going in the right direction, supporting the managers.

‘Celtic haven’t really had that. Maybe it’s time to start looking at it and being restructured in a different way. To give the fans the opportunity to believe that the club will go in the right direction.’

Bluntly, there’s little hope among the rank and file that the current occupants of the boardroom have the wherewithal to deliver the necessary change.

Throughout the whole episode, as one disastrous decision has followed another, the lack of responsibility taken from those in the heated seats has been astonishing.

As he took a flame thrower to Brendan Rodgers’ character, Dermot Desmond’s claim that there was nothing wrong with the ‘structure or model’ of the club seemed detached from reality.

At least Celtic’s largest shareholder said his piece. Aside from some cosy in-house chats, chief executive Michael Nicholson has been about as vocal as a Trappist monk.

‘You need strong leaders in difficult times,’ said Petrov. ‘At the moment, it seems like there’s nobody out there leading in the right direction, doing the right things, trying to calm things down and give the opportunity for the fans to settle and the team to start performing.

Stiliyan Petrov insists that his former club need to be restructured if they are to thrive again

Petrov, pictured above with O’Neill in happier times at Celtic, feels his former boss shouldn’t have taken on the job again

‘There’s not a clear message of who makes the decision, who finds players, who signs the players, who makes plans of what’s happening. At the moment, you don’t know.’

While interim chairman Brian Wilson has at least attempted to communicate with disaffected fans through a series of meetings, it feels akin to putting a sticking plaster on a gaping wound.

About to turn 74, Martin O’Neill has been left to field questions pertaining to fan protests when he should only be concerned with getting a tune out of the team. Petrov feels this burden is fundamentally unfair.

‘It’s great to see him, but I have kind of felt sorry for him,’ he said of his former boss. ‘He’s 73-years-old and he’s trying to save the club at a difficult time.

‘He’s trying to motivate, trying to be the connection between the fans and the board and trying to do his job with the team on the pitch.

‘It’s really sad to see. If I’m a Celtic fan – and I am a Celtic fan – I would like to see Martin doing more than being asked to save the club in this moment.

‘That’s not his job. The club should really have made better decisions than asking Martin to stay and save the season.

‘Fair play to him. If it was me, I’d never do it. He’s done great, he’s cut the gap. But if he doesn’t win the league, what does that mean?

‘What will the fans think about it? Because, if you don’t win the league, you are a failure.

‘The fans might not see it that way, but I know Martin will feel he could have done better. It seems like all of the pressure right now is on Martin. He is trying to deal with so many things. The club is divided. He doesn’t need that now.’

Come what may, Petrov would like to see O’Neill remain involved at Parkhead in the longer term in some capacity.

Whether the veteran would countenance taking another role – particularly in the current climate – remains to be seen.

Second guessing anything at Celtic right now is nigh impossible. When the plan for long enough has been so hard to discern, it’s dangerous to assume that anyone on high has an incline of what the future should look like.

‘Martin is there to the end of the season and he’ll take the hits and the questions,’ said Petrov.

‘But what happens next? There’s no clarity. It needs a clear plan of action. What is happening here? What happens next? Who leads?

Celtic boss O’Neill makes his feelings known during the 2-1 defeat to Hibs last Sunday

‘There’s not a clear message to the fans. That’s where the fans get frustrated. It’s about what we do next, but no one knows what’s happening.

‘That’s where the big leaders – the chairman, the chief executive – stand up.

‘If you make a mistake, and we all make mistakes, you have to take it as a man.

‘You show leadership, you are proactive. What is the action plan and how are you are going to execute it?

‘At the moment, there is no message like that. A good leader communicates and is clear about what they want to achieve and how he’s going to achieve it.’

■ Stiliyan Petrov was speaking on behalf of William Hill, the SPFL’s title partner. Check out the weekly preview show here: