It has been a quieter summer than most Celtic supporters would have hoped for at Celtic Park. Colombian striker Camilo Duran, signed from Azerbaijani club Qarabag, remains the sole incoming deal as Martin O'Neill attempts to reshape a squad that came uncomfortably close to surrendering the Scottish Premiership title to Heart of Midlothian last season. And now, with O'Neill reportedly resigned to selling Arne Engels and Daizen Maeda — and planning talks with club captain Callum McGregor following his reported switch of agency — the mood among the support has darkened further.

It is worth taking a breath and asking, calmly, what the loss of these three players would actually represent. Because the honest answer is: quite a lot.

Arne Engels — the heir apparent who found his feet

When Engels arrived from Bundesliga side Augsburg in the summer of 2024, the comparisons with Matt O'Riley — sold to Brighton for significant money after 19 goals in 49 appearances the previous campaign — were unavoidable and, frankly, unfair. O'Riley himself took time to settle before his output exploded. Engels, 22 and capped four times for Belgium, appears to be following a similar trajectory.

Ten goals in his debut season and seven the term before show he can contribute regularly from midfield, and crucially, his most recent strikes arrived in the moments that mattered most — the final-day Premiership showdown with Hearts and the Scottish Cup final victory over Dunfermline Athletic. Add eight assists in a single season and it becomes clear that Engels is not merely a squad player; he is a decisive one. Nottingham Forest's reported interest last term underlines what the wider market already suspects.

Daizen Maeda — the closer-down who keeps scoring

Ange Postecoglu, speaking during the summer cup finals, described Maeda's pressing ability as nothing short of world-class, and the numbers do not argue. The Japanese forward reached 33 goals in 51 appearances in the 2024-25 season — a genuine peak — but this was not a one-season wonder. He has been in double figures across each of his three other full campaigns, and his 38 assists over the course of his Celtic career have been as important as the goals themselves in delivering ten pieces of silverware, among them five league titles.

At 28, Maeda arguably has his best football still ahead of him, and a reported move to Wolfsburg earlier this year fell through without completion. With only a year remaining on his contract, Celtic face a genuine dilemma: sell now or risk losing him on a free. That is not a comfortable place to be.

Callum McGregor — the heartbeat who cannot simply be replaced

Some players lend themselves to replacement by statistic. McGregor is not one of them. Yes, 77 goals and 84 assists in 576 Celtic appearances since his breakthrough in 2014 are remarkable figures. Yes, 26 honours — including 11 league titles — place him among the club's all-time greats. But those numbers do not capture what he actually does, the daily leadership, the reading of a game, the steadying presence that has made him the natural successor to Scott Brown as captain since 2021.

At 33, McGregor is entering the final chapter of his career, and he acknowledged in April that his long-term commitment to Celtic was conditional on the club continuing to push for success. The late-season surge that prised the title away from Hearts' grasp will have been reassuring. Still, with a contract running until 2028, there remains a window for one significant move if the right offer arrives.

What comes next?

Celtic open their Premiership title defence at home to Dundee on 3 August, with a trip to Kilmarnock to follow shortly after. O'Neill has precious little time to find replacements for players who, between them, have shaped the architecture of the club's recent dominance. The market will sense vulnerability. The supporters will demand clarity. And somewhere in all of that, Celtic need to show they can absorb significant losses without the sort of wobble that nearly cost them everything last season.

Frequently asked

Why might Celtic sell Arne Engels this summer?
Reports suggest Martin O'Neill has accepted that Engels could leave Celtic Park, with clubs including Nottingham Forest having previously shown interest. At 22 and contracted until 2028, he represents a saleable asset, though his importance to the squad makes any departure a significant blow.
How many goals has Daizen Maeda scored for Celtic?
Maeda scored 33 goals in 51 appearances during the 2024-25 season, his best campaign to date. Across his time at Celtic he has also contributed 38 assists and won ten trophies, including five Scottish Premiership titles.
Is Callum McGregor leaving Celtic?
Nothing has been confirmed. O'Neill is reportedly planning talks with McGregor following the captain's reported move to a new agency. McGregor is contracted until 2028 but has indicated his long-term future depends on Celtic remaining competitive.