Glasgow Rangers had enjoyed a relatively solid start to the season before the visit to Parkhead on Saturday afternoon for the Old Firm derby.

The Ibrox side capitulated, with a team performance way below what is expected and a few goalkeeping errors totally destroying all momentum the side had built up by qualifying for the Champions League group stages.

A 4-0 defeat leaves the supporters with many questions, not just for the manager but for Ross Wilson and the boardroom, with the vast majority of the Ibrox faithful expecting at least one new arrival on deadline day, especially considering the riches guaranteed from the Champions League.

What makes it even worse is one of the Celtic substitutes in the match might well have been a Rangers player this summer.

Wilson had a summer howler

Former Gers defender Craig Moore claimed that he tried to convince Wilson to make a move for now Celtic player Aaron Mooy, and it appears to be a decision that he could well regret considering the qualities the Australian possesses and how easy he has settled into life at Celtic.

Moore said back in July: “He's a fantastic player, and you touch on experience, I think that is key as to why Aaron has ended up at Celtic.

“I think it's really good business. I know the player extremely well. He has played at the highest level, and the ability to get about the park and (has) a range of passing and delivery. He is a really, really good player.

"I will be honest, he is one I tried to push to Rangers first. With the quality of the player (it made sense), but with the position that are being filled at Rangers and he is slightly older, maybe it didn't make a lot of sense.”

It looks a good move in hindsight, but Van Bronckhorst was busy signing Tom Lawrence and Malik Tillman to improve other areas. However, as the window progressed, a midfielder in the mould of Mooy didn’t materialise.

With the Gers midfield being completely overrun in the Old Firm clash, it's clear a player such as Mooy – who Thierry Henry dubbed “special” when he was at Huddersfield – might well have made a difference in the engine room.

Indeed, per the Daily Record's player ratings, none of Rangers' three central players earned a rating above a 5, with John Lundstram failing to 'dominate' and Glen Kamara being dragged off at the break.

The 31-year-old Mooy has a pass success rate of 90% in his six appearances this season, making on average one tackle per game and winning an impressive 71% of his total duels.

That is better than the aforementioned Kamara and Lundstram who have won just 54% and 49% of their total duels on average respectively.

Despite the match already in the bag when the Australian came on for the final 17 minutes against Rangers, he won 66% of his duels and had 13 touches, showing his willingness to get involved and contribute.

It was a dreadful display overall by Rangers but having someone in the shape of Mooy to rejuvenate a stagnating midfield might have changed the course of the game.

Instead, Wilson will have to ponder why he didn't heed Moore's suggestion a few months ago.