Celtic do not always hit the mark with their work in the transfer market and there have been times when they have failed to replace some of their star players.

In the 2025/26 campaign, for example, the Hoops had to play left winger Daizen Maeda as a centre-forward on a regular basis because they had failed to bring in a quality replacement in the number nine role.

The Scottish Premiership giants sold Adam Idah to Swansea for £6m in the summer of 2025 and only replaced him with Kelechi Iheanacho, who was only fit enough to play 13 league matches.

That came after Celtic had already downgraded their attack by replacing long-serving centre-forward Kyogo Furuhashi with Idah under Brendan Rodgers.

Why Idah was a big downgrade on Kyogo

Kyogo's best season in a Hoops shirt came in the 2022/23 campaign when he scored 34 goals in all competitions, including an eye-catching haul of 27 goals in the Premiership.

As the Japan international headed towards the end of his Parkhead career, the club signed Adam Idah on loan from Norwich City in February 2024 before joining permanently for £9.5m later that summer.

The Irish centre-forward was unable to step up to the standard that Kyogo set at Parkhead, unfortunately, and ultimately proved to be a downgrade on what the club had in that position.

Idah had his moments, scoring 13 goals in the league in the 2024/25 campaign, but he did not come close to the level of output that made the player he was aiming to replace such a loved figure in Glasgow.

The former Norwich star was then sold to Swansea for £6m after just one full season at the club, which meant that the Hoops took a £3.5m loss on the striker a year after signing him for £9.5m.

Celtic have found their biggest downgrade since Kyogo to Idah

In the present day, Martin O'Neill has a similar issue at the top end of the pitch, but in a different position, as they have their biggest downgrade since they went from Kyogo to Idah.

Earlier this month, the Scottish giants were hit with a blow when Hyun-jun Yang had to jet away for the Asian Games with South Korea, after he had started the campaign in fine form.

The 24-year-old winger scored in each of his last two appearances in the Premiership, after ending the 2025/26 campaign with eight goals and six 'big chances' created in the division.

Unfortunately, Celtic failed to build a squad with strength in depth in every position and the replacement for Yang has yet to prove that he is good enough to be a starter for O'Neill.

In the summer of 2025, Rodgers swooped to sign Sebastian Tounekti from Hammarby for a fee of around £5m to bolster his options on the left wing, but he has struggled since making the move to Glasgow.

The Tunisia international started in the 3-0 loss to Rangers on Sunday and was substituted at half-time after an anonymous 45 minutes, making it seven matches without a goal or an assist in all competitions for the forward.

In 33 appearances in the league since the start of last season, Tounekti has only contributed with two goals and two assists for the Hoops, which is not good enough for a forward playing in a dominant team.

Celtic won the league in the 2025/26 campaign and dominated matches week-in-week-out, yet the winger was unable to register more than two goals or two assists.

Yang has scored eight more goals and created three more 'big chances' in the league since the start of last season, which speaks to the difference between the two players.

In fact, the South Korean attacker has scored as many league goals in his last two appearances in the division as Tounekti has managed in 33 matches for Celtic.

On current evidence, Tounekti looks like a waste of £5m because he has not proven that he has the quality to be a reliable performer for the Hoops, as shown by the fact that he was taken off at half-time against Rangers on Sunday.

The Tunisian forward looks like the club's biggest downgrade since they went from Kyogo to Idah, because of how little he offers in comparison to Yang, and it is a problem that may have to be looked at in January.