Is it time for Celtic's Matt O'Riley to be rotated?

It is a matter of opinion, of course, that O'Riley's recent performances have dipped since Celtic returned to action after the World Cup finals break but even if they have that doesn't necessarily mean he is having a bad season, does it?

Is it now a legitimate question to ask whether Ange Postecoglou should rotate O'Riley in favour of Aaron Mooy for instance?

On a base statistical level, O'Riley and Mooy have featured in 20 and 18 Premiership matches respectively this season. The former has clocked 1,558 minutes of first-team league action with Mooy playing for a total of 818 minutes.

Disappointingly O'Riley has zero goals for the campaign but has contributed eight assists while Mooy has two goals to his credit and four assists.

Here is where it's all about perception. Although to the naked eye it would appear that O'Riley is struggling to find his form of the past, he is very effective - crucial even - in making the Celtic system under Postecoglou function.

READ MORE: Why Matt O'Riley is the perfect Celtic poster boy for Ange Postecoglou

And O'Riley has certainly not been underperforming for long. One has to remember that Postecoglou turned to him to fill in the void in the number six role created by McGregor's absence through injury. He adapted superbly to the position which allowed Celtic to continue to play the same brand of attacking football. In McGregor's absence, the team did not ship a solitary Premiership point while O'Riley was deployed in a deeper role.

According to the Opta, up until the Rangers game O'Riley was creating some 7.63 chances per 90 minutes. Those are big and effective numbers. The stats don't lie when they say that O'Riley is Celtic's best chance creator and he has achieved all of this while being asked to function in a newer deeper unfamiliar position for a considerable time. He also attempts far more creative passes than any other midfielder and loves a tackle too, which is an area where he has improved his game immensely. Sometimes the unglamorous work can go unrecognised.

Yet there seems to be a school of thought out there that O'Riley is not offering enough in the scoring contribution stakes at this particular juncture. One would conjecture that O'Riley desperately needs a goal himself to quell the growing voices of discontent.

Perhaps most noticeable of all, though, was the fact that Monday's Glasgow Derby was O'Riley's 18th consecutive start for Celtic.

When it comes to player rotation, Postecoglou has been frank on the matter, saying: "It's an important part of us as a team, that the guys are prepared to put the shift in when required. Everyone wants to play every game but it's impossible to do. If we are going to maintain the levels of performance that we need with the schedules we have, we need players out there all the time with energy.

"Knock on wood, our medical team and sports scientists have done an outstanding job this year in terms of keeping our best players on the park all the time and it has helped that I have been able to rotate the squad and keep players fresh. Aaron (Mooy) coming in has helped us enormously as well. Aaron has come back from the World Cup in great condition. We have got really good players and we are going to utilise them."

Note the mention of Mooy and his recent contribution - which cannot be underestimated. "I know he (Mooy) is a quality player and I'm really pleased because we gained a good player for our squad. I knew he could contribute," Postecoglou said as far back as October.

After his impressive brace against Hibs on December 28, when the midfielder was given the ultimate honour when the Celtic fans dedicated a song to his name, Postecoglou again commented on his situation.

"With Aaron, it was just a matter of getting him fit," he said. "He played probably two games of football in six months before we signed him. So I knew it was going to take time when to get to the fitness levels but I knew as soon as that happened he has such a good engine, his ability to run, and his quality would eventually shine through.

"We’ve had a positive World Cup, the guys who went away have come back with some real belief through the positive experiences they had. I think that has helped us, not just with the players’ own conditioning, but also in their belief in themselves. It was great for Aaron, he’s been a bit unlucky, he’s been knocking on the door at getting a couple of goals and it was great to see him do it.”

READ MORE: How clever Aaron Mooy cameo swung derby day back in Celtic's favour

That led to many Celtic supporters being miffed that the 32-year-old was left out of the Hoops starting XI for Ibrox. However, what a telling contribution Mooy made when he came on in Govan though.

It was his intelligent run and dart into space from Jota's reverse pass that kept the move that led to Kyogo Furuhashi's late leveller alive. Simply put, the Australian put in a shift when required.

As has O'Riley whenever he has been asked to step up to the plate this season. At this moment in time, Mooy appears to be the flavour of the month in the eyes of the Hoops faithful and his run of form is a big factor in the supposed clamour among fans for O'Riley to be rested.

The Socceroos midfielder may well have come back from the World Cup in great condition but, one thing is for certain as the derby team selection showed, the manager won't be swayed by public opinion.

So the answer to the question will Mooy now start more games in midfield because O'Riley needs to be rested - or if O'Riley should even be rotated at all - doesn't really matter, does it?

Is it time for O'Riley to be rotated? Ultimately, that's best left for Postecoglou to decide.

As the manager himself said, Celtic have got really good players and are going to utilise them. Maybe that's a big part of the reason why they're champions.