Recent comments from Martin O’Neill have done little to ease concerns among Celtic supporters regarding the club’s quiet summer transfer window. Colombian striker Camilo Duran, signed from Azerbaijani side Qarabag, remains the Scottish champions’ only addition so far, despite the manager’s clear intention to rebuild his squad after nearly losing the league title to Heart of Midlothian last season.

O’Neill has reportedly admitted he has resigned himself to the potential departures of Arne Engels and Daizen Maeda. Furthermore, he plans to hold discussions with captain Callum McGregor regarding his future, following reports that the midfielder has reportedly signed up to a new agency.

This report examines the impact these key players have on the Glasgow club and the potential consequences of their exit.

Impressive stats, numerous medals

Arne Engels arrived in the summer of 2024 from Bundesliga club Augsburg. While not a direct tactical replacement, the midfielder effectively stepped into the role vacated by Denmark international Matt O’Riley, who moved to Brighton & Hove Albion after a productive season featuring 19 goals in 49 appearances.

The 22-year-old Belgian international has yet to match those scoring figures, though O’Riley similarly took time to settle after his 2022 arrival. Engels showed his potential by netting 10 goals in the 2024-25 season and seven the previous term.

Notably, his two most recent strikes came during trophy-winning performances: the final-day Scottish Premiership decider against Heart of Midlothian and the Scottish Cup final win over Dunfermline Athletic. With eight assists last season, he has proven his value to Celtic’s recent trophy haul.

Forward Daizen Maeda enjoyed a standout 2024-25 campaign with 33 goals in 51 matches. He has reached double figures in every full season at Celtic, including 17 goals in 2025-26. His contribution extends to 38 assists, which helped secure 10 pieces of silverware, including five league titles, during his tenure.

Meanwhile, the importance of Callum McGregor remains unquestioned. As one of the club’s most decorated captains, he boasts 26 honours, including 11 league titles. Since his 2014 breakthrough, the former Scotland midfielder has recorded 77 goals and 84 assists in 576 appearances.

Intangible qualities, attractive options

Beyond the statistics, leadership and experience define these players. At 33, McGregor provides crucial guidance, while 28-year-old Maeda and the younger Engels represent long-term assets. Former manager Ange Postecoglou previously praised Maeda’s “world-class” pressing ability, while McGregor has served as the team’s heartbeat since taking the captaincy in 2021.

Their quality makes them targets for other clubs. A move to Wolfsburg for Maeda fell through previously, while Nottingham Forest expressed interest in Engels last season. Although both saw their form dip momentarily after failed transfers, they finished the year strongly.

Speculation surrounding McGregor is standard given his 12-year career at the club. While he once prioritised his Celtic form by retiring from international football, he noted in April that his desire to finish his career in Glasgow depends on the club’s ambition. Both he and Engels are under contract until 2028, but with Maeda’s deal expiring in one year, Celtic faces a limited window to secure a transfer fee.

What is manager O’Neill saying?

Celtic begin their Premiership title defence at home to Dundee on 3 August, followed by a trip to Kilmarnock and a League Cup fixture. The club is also preparing for a crucial Champions League play-off round in late August, where they hope to avoid a repeat of last season’s exit.

O’Neill, who extended his stay after serving as interim manager, recently told Celtic TV he aims to “augment the squad.” Since then, the club has secured Duran and signed new contracts with Alex Oxlade-Chamberlain, James Forrest, Luke McCowan, and Liam Scales.

Regarding his tactical approach for the 2026-27 season, O’Neill stated: “When we have possession of the ball, it’s great to keep it and absolutely right, but I’d like us to keep it for a purpose.” While the manager remains coy, losing Engels or McGregor would create a significant void in midfield, and a departure for Maeda would leave a major gap in the attack.