Celtic did not have a perfect summer transfer window, as they failed to land any strikers on deadline day, but they did do some good business on the whole.
Bringing Kieran Tierney back to the club on a free transfer from Arsenal was arguably the highlight of the window on paper, six years on from his £25m move to Arsenal in the summer of 2019.
The Scotland international was the first signing of the window and the highest-profile addition to the squad to replace Greg Taylor for Brendan Rodgers.
How Kieran Tierney has performed for Celtic
Expectations were, understandably, high for the left-footed star after what he achieved during his first spell at the club, and the fact that he has played in the Premier League and LaLiga over the past six years.
The 28-year-old full-back has not had a perfect start, losing 100% of his ground duels in the second leg against Kairat for example, but that should have been expected given his injury issues in recent years.
Tierney missed 45 matches through injuries in the 2023/24 and 2024/25 campaigns combined, per Transfermarkt, but he has still shown glimpses of the quality that he can provide, with an excellent assist against Aberdeen in the Scottish Premiership.
Whilst it has been exciting to see such a high-profile player return to Celtic this season, Tierney is not the most valuable full-back in the squad – Alistair Johnston is.
Celtic have hit the jackpot with Alistair Johnston
Ange Postecoglou signed the Canada international from Montreal for a reported fee of £3.5m in January 2023, and the Australian head coach hit the jackpot for the club with that move.
The impressive right-back, whose work rate was hailed as “phenomenal” by Rodgers, has gone on to play 115 times for the Scottish giants in all competitions, per Transfermarkt, and registered 22 assists.
Johnston did not have a Transfermarkt market value at the time of Tierney’s £25m move to Arsenal in 2019. Now, six years later, the Canadian star is worth even more than the Scotland international.
August 2019
£25m move to Arsenal
N/A
July 2020
£24m
£43k
May 2021
£28m
£2m
May 2022
£28m
£2.5m
June 2023
£21m
£6m
March 2024
£10m
£7m
October 2024
£9m
£8m
June 2025
£8m
£9m
As you can see in the table above, the 26-year-old star is worth more than the Scottish defender for the first time in their respective careers, which speaks to his rise and the fall of the left-back.
This also shows that the Hoops hit the jackpot with the right-back because his value has soared from £3.5m to £9m in less than three years, making him a far more valuable asset than he was when they signed him from the MLS.
Johnston, who is currently out injured, has proven himself to be a huge attacking threat from right-back for Celtic, creating 15 ‘big chances’ in 30 league starts last term, per Sofascore.
His superb performances on the pitch for the Scottish giants have led to his market value soaring to the point that he is now worth even more than Tierney, who was once a £25m-rated player.
Overall, Postecoglou hit the jackpot for Celtic by signing him from Montreal and the club will be hoping that he can continue to deliver on the pitch to increase his value by even more.
