Boss Derek McInnes insists enough time was given to Craig Bryson to turn around his injury hit Aberdeen career.
Midfielder Bryson was McInnes’ marquee signing of last summer having left Championship side Derby.
However, the 33-year-old this week left Aberdeen having had the remaining nine months of his contract cancelled.
Scotland international Bryson was dogged by injury misfortune during his time at Pittodrie and made just 14 appearances.
He signed while recuperating from an ankle injury suffered towards the end of the 2018-19 campaign with Derby.
Having recovered from that setback, Bryson was then hit by an injury to the other ankle that subsequently required surgery.
McInnes said: “We gave it a decent length of time to try and make it a success.
“Both Craig and I along with the medical team were desperate for him to give us a bit more.
“But sometimes you have to hold your hands up and say this is not working.
“We wish Craig well.
“He was the boy I thought I was signing in terms of willingness and attitude.
“But the challenges he faced can sometimes beat you.”
Bryson started just eight games for the Dons.
McInnes insists the failure of Bryson to make the expected impact at Pittodrie was not through lack of effort or desire on the midfielder’s part.
He said:”Craig could not have put anyone more into it.
“He was desperate to be a success here, as we all were.
“He was a major signing for us and a very good signing.
“I think unanimously when we signed him we looked it at it that way.
“Craig was someone I felt would give us leadership qualities and drive on the pitch after losing Graeme Shinnie, as he’s done throughout his career.
“It’s just so unfortunate.
“I think there comes a point where I understand why Craig gets frustrated, it is just one thing after the other.”
Aberdeen will on Saturday bid to extend a winning streak to five games when facing Kilmarnock at Pittodrie.
Winger Matty Kennedy has recovered from a back complaint which saw him pull out of the Northern Ireland squad for the Nations League tie away to Romania (1-1 draw) last week.
McInnes said: “Matty is fine and trained on Thursday.
“The lads who were away with the Scotland U21’ (1-0 Euro qualifying away win in Lithuania on Tuesday) are all good.
“Obviously Ross McCrorie and Lewis Ferguson got a lot of playing time with the U21s.
“Ross got a couple of bangs, but is OK and will train today.
“No one from the international set-up has any issues and Scott (McKenna) trained as well.”
McInnes also confirmed on-loan Leeds United striker Ryan Edmondson will return to Pittodrie next week.
England U19 international Edmondson has been at parent club Leeds since suffering an ankle injury during training in early August.
McInnes said: “Ryan will come back to us next Monday from Leeds.
“We will assess where he is.
“We are confident we will get him back sooner than we originally hoped. He certainly won’t be training next week, but he’s coming up.”