Boss Barry Robson says Aberdeen have yet to find a solution on how to balance the demands of European and domestic commitments.
The Dons slumped to a 2-0 defeat at Kilmarnock just three days after losing to PAOK in the Europa Conference League.
In the five Premiership games immediately following Euro fixtures this season, the Reds have won just once, drawing two and losing two.
Aberdeen languish 10th in the Premiership table with a return of just nine points from nine league matches.
Robson accepts the Dons’ league form is “not good enough”.
In the Europa Conference League, the Reds have taken just one point from three games, and blew a two-goal lead in the 3-2 loss to group leaders PAOK on Thursday.
In the immediate aftermath of Sunday’s Kilmarnock loss, Robson accepted culpability for not rotating his squad enough after the PAOK match.
Aberdeen underwent a major squad rebuild in the summer with 13 signings secured to help cope with the demands of Euro and domestic action.
However, Robson made just one change to the starting XI to face Kilmarnock from the line-up that faced PAOK.
Robson admits the Reds have yet to effectively deal with fighting on two fronts – and warned it must change immediately.
He said: “If you want to play at this level, play in Europe and go far in cups, you need to deal with that.
“We’ve not dealt with it so far, so we need to start doing that better
“Our league form hasn’t been good enough.
“It’s been stop-start with games being cancelled or moved.
‘It wasn’t a good enough performance from us against Kilmarnock.
“Across the board, we need to be better.”
Costly price of individual errors – but ‘Stefan has been outstanding’, says Robson
Defensive errors have been costly in the back-to-back defeats against Kilmarnock and PAOK.
With Aberdeen 2-0 up, a slip by Richard Jensen and then a poor header from Jonny Hayes led to PAOK’s first two goals.
A clumsy tackle by Slobodan Rubezic in injury time then led to a penalty (following a VAR review) that was converted by the Greek Super League side for the winner.
Again an individual mistake was exploited against Kilmarnock, when a poor clearance by Stefan Gartenmann was charged down by Marley Watkins.
Former Aberdeen striker Watkins converted to put the Rugby Park side 2-0 up.
The biggest things in football is fatigue, that’s what causes mistakes.”
Aberdeen manager Barry Robson
Centre-back Gartenmann is on a season-long loan from Danish top-flight club FC Midtjylland.
Robson has already confirmed he aims to sign Gartenmann beyond that.
Gartenmann is contracted to the Danish Superliga club until summer 2025.
Robson refused to criticise Gartermann for the error, and is confident the loan star will bounce back.
He said: “The biggest thing in football is fatigue, that’s what causes mistakes.
“I’m not going to dig players out as we all make mistakes.
“It’s just that in the last couple of games they have been unfortunate – for a different player, for a different reason – which happens.
“Stefan made a mistake, but he has been absolutely outstanding since he has been here.
“Richard Jensen was brilliant against Kilmarnock, but slipped the other night (against PAOK).
“Stefan is an experienced player, and these things happen.
“That happens in football, but you just hope they don’t all happen at the same time.
“That’s what has been catching us lately. These little things cost us.
“A lot of it has just been individual errors that have cost us in the last two games.
“We all make mistakes – I made a mistake by not freshening the team up.”
Conversation