Celtic spent around £31m last summer, a huge outlay even for a club the size of the Hoops.

They broke their transfer record twice across the window, spending an initial £8.5m on Adam Idah and then £11m to recruit midfielder Arne Engels.

The third-most expensive signing was £6m man Auston Trusty from Sheffield United, as Brendan Rodgers sought to strengthen the left side of Celtic’s central defence.

However, bar a few games, Trusty hasn’t really lived up to that price tag yet. Liam Scales is Celtic’s other left-footed centre-back and while he has impressed at times, he isn’t consistent enough.

Both are nowhere near the consistency or quality of Cameron Carter-Vickers, and Stephen McGinn thinks as a result, Celtic keep on failing to find a long-term partner for the American.

Photo by Emmanuele Ciancaglini/Ciancaphoto Studio/Getty ImagesPhoto by Emmanuele Ciancaglini/Ciancaphoto Studio/Getty ImagesStephen McGinn on Liam Scales and Auston Trusty

McGinn was speaking on The Go Radio Football Show and was initially asked by host Rob MacLean if Scales could have done better to stop Cyriel Dessers from scoring in the Glasgow derby on Sunday.

The Rangers striker outmuscled and outmanoeuvred Scales before firing a shot into the net past Viljami Sinisalo to put the Ibrox side in front.

McGinn thought Scales should have prevented Dessers, as well as highlighting Celtic’s need to sign a better quality left-footed centre-back.

The pundit said: “I thought just off the back of the Bayern game, how good Carter-Vickers and Trusty were as a partnership and obviously spending a lot of money on Auston Trusty, I just assumed that would be the partnership.

“Brendan Rodgers has brought Liam Scales back into the team and I think he’s been good in the games, but he has struggled in those types of fixtures.

“I think he’s got to do better, I think he’s got to do more to stop the shot getting away. I think with Dessers, he could easily shuffle him wide but he’s ended up on the ground.

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“And we’ve probably said it for the last couple of summers, it’s an area of the park (left centre-back) Celtic have to get right.

“Cameron Carter-Vickers is a top level centre-half, but it’s that one position that they still go into every summer thinking ‘we need to get that one right’.”

Trusty vs Scales at Celtic this season

Trusty and Scales have interchanged this season for several different reasons, but neither have managed to solidify that left centre-back slot.

Hugh Keevins recently branded Trusty “a waste of money” alongside Adam Idah, while Scales is now being criticised for his defending against Rangers.

CategoryAuston TrustyLiam Scales Position Centre-Back Centre-Back Total Appearances 35 36 Goals 1 3 Assists 1 4 Yellow Cards 2 2 Red Cards 0 0 Minutes Played 2,958 2,555

Both Trusty and Scales actually rank highly on Sofascore’s average ratings for the season so far, but Celtic fans won’t be in the same school of thought.

Rodgers has confessed ‘change is needed’ in his first-team squad for next season, so will he once again shell out to sign a left centre-back, or stick with what he has?