Paul Dickov was critical of his side following its second-half capitulation in a 4-1 npower League One defeat at Bournemouth.
Former Latics’ loanee Lewis Grabban was the architect of their downfall scoring a 19-minute second half hat-trick.
"It was disappointing and embarrassing, especially the second half, and I won’t be forgetting it for a long time," explained Latics’ manager after seeing his side slip into the bottom four.
Dickov continued: "To concede the goals in the manner we did is more than disappointing. I am embarrassed for the fans who travelled a long way and didn’t deserve that.
"We might have good footballers but, if they are mentally weak, they are not going to have a chance.
"After the first goal went in, which should never have happened as our back four backed off ten yards to let them have a shot, we just crumbled.
"I have told them if they cannot concentrate for 90 minutes they might as well not be here. I keep banging on about what good players we have here, but I seriously question their mentality.
"A lot of my players tell me they want to play in the Championship, but today they showed me why they are not there."
Dickov pinpointed how they were punished for not reacting to defensive danger saying little things and fine lines make a difference.
He added Bournemouth are the best side Latics have faced this season and he expects them to be challenging at the top end of the table, but that doesn’t make excuses for their second-half performance.
Latics had a new look central-midfield pairing of Robbie Simpson and Youssouf M’Changama as Dean Furman and James Wesolowski were both ruled out through suspension.
The other change from last Saturday saw Jean-Yves M’voto return to the centre of defence after completing a three-match ban. H e replaced James Tarkowski.
After a goalless opening period, in which neither goalkeeper had a save to make, Latics more than matched the Cherries. There was no inkling at the break as to the horrors would lie ahead in the second period.
It took until the 49th minute before Dean Bouzanis was called into action with a comfortable save to deny Josh McQuoid.
Bournemouth made the breakthrough four minutes later when Harry Arter’s shot was going wide until Grabban managed to divert it high into the net past Bouzanis.
Latics needed to consolidate but barely 60 seconds later, they found themselves 2-0 behind.
McQuoid was the provider with a low cross from the right and Grabban provided the deftest of touches to glance a shot low into the far corner.
Dickov quickly made a double substitution as Simpson and Lee Croft were replaced by Matt Smith and scholar Chris Sutherland.
Jose Baxter forced former England keeper David James into his first save of the game midway through the half as he dived low to his left to keep out his 25-yard drive.
The afternoon got worse for Latics in the 72nd minute when M’voto fouled Arter to concede a penalty.
Arter’s spot kick was brilliantly saved by Bouzanis low to his left only for Grabban to react quickest to fire home the rebound.
Carl Winchester replaced M’Changama with 13 minutes left as Latics made their third and final substitution.
Latics’ defence was pierced for a fourth time in the 82nd minute when left-back Charlie Daniels was left completely unmarked at the far post to head home Marc Pugh’s free kick.
Smith scored a consolation goal with four minutes left, a well directed header from a Sutherland cross as the two substitutes combined superbly.
Sadly it was a case of too little, too late for Latics whose match at bottom club Hartlepool on Tuesday now assumes even more importance.
Bournemouth (4-4-2): James; Francis, Elphick, Addison, Daniels; McQuoid , Arter (O’Kane 79), MacDonald, Pugh; Grabban (Fogden), Barnard. Subs (not used): Jalal, Fletcher, Tubbs, Cook.
Latics (4-4-2): Bouzanis; Wabara, M’voto, Byrne, Grounds; Croft (Sutherland 58), Simpson (Smith 58),M’Changama (Winchester 77), Montano; Derbyshire, Baxter. Subs (not used): Cisak, Brown, Tarkowski, Hughes.
The goals: Grabban (53, 54, 72), Daniels (82) for Bournemouth. Smith (86) for Latics.
Bookings: Arter (18) for Bournemouth. Grounds (15), Baxter (69) for Latics.
Referee: Mr S Rushton.
Attendance: 6,118 (209 visitors).