David Healy admits "I got it wrong" after watching Gletoran put his side to the sword on Friday night.
Linfield were second best all over the pitch as the Glens claimed a commanding 3-0 win at Windsor Park.
The Blues weren't helped by Michael Newberry's dismissal in the 31st minute, but goals from Bobby Burns and Danny Purkis (2) were deserved reward for Mick McDermott's impressive visitors.
Read more: Glentoran flex title muscle with 3-0 win over Linfield at Windsor Park
Healy accepts the blame firmly lays at his doorstep, with Linfield's disappointing early season form suffering another significant set-back.
Asked if he could put his finger on his side's patchy start, Healy said: "Absolutely not.
"I wish I could. At this point I can't. I know people will be demanding that I do find out quickly.
"I turned round to the supporters. I am there. I'm our leader, I'm our manager. I'm there to be shot at and there to be helped - or not helped - at times.
"Sometimes the frustration gets the better of myself and sometimes the frustrations get the better of some of the supporters who are wanting things to happen.
"But I have always said my fault. I have never come in here and blamed someone for missing a penalty of getting sent off.
"I take full responsibility as the manager. I take full responsibility for the level we play at and I take full responsibility that our fitness levels weren't good enough tonight.
"I take full responsibility for the changes I could have made and didn't make until after the second goal. I take full responsibility for the team I selected tonight which I thought would have been good enough.
"In the end, and looking at it after the game, I got it wrong. And we let the supporters down tonight.
"So I understand their frustrations more than anyone. I get it."
READ NEXT:
- Ireland women's team apologise after singing pro-IRA song after World Cup result
Baraclough believes Euro draw offers NI chance to repeat 2016 heroics
Fans rally around family of NI football supporter who died abroad
Sign up to our free sports newsletter to get the latest headlines to your inbox.
