Shaun Williams said the defence fell foul by playing out of position after two mistakes cost Dons two goals away at Preston on Saturday.
A slip from the Irishman after 12 minutes allowed Chris Humphrey to cross and it cannoned in off Antony Kay.
Jason Banton scored a wonder goal to equalise on the half hour, but when Jon Otsemobor, deployed at centre back rather than his customary right back role, sold short his pass back to David Martin, Joe Garner restored Preston’s lead three minutes later.
A second half penalty from Williams restored parity once more, and Dons could have gone on to win it with the chances they created.
But Williams admitted the mistakes cost them all three points, and said they came out of inexperience in their positioning.
“These things happen. Luckily we rectified it with two equalising goals and I think with an extra five minutes we could have snatched the three points.
“People were playing out of position and we looked a little bit out of sorts. I don’t think Otsemobor knew someone was behind him, but if he was at right back he’d have known. It just takes time to get used to a new position.
“Everyone has to play where they’re told but you get used to it in the end.”
Williams though felt 2-2 was a fair result, but felt Dons were the only side capable of winning it in the second half.
He said: “It was an interesting game to play in. End-to-end, both teams gave it real go.
“Two all probably nailed it on the head. If he had another five minutes we were making more changes than they were.
“But I’m happy enough with a point, especially up here, where the fans expect Preston to get three points. Davies is so effective at what he does, and they play to that strength.”
Jason Banton received a round of applause from the Preston fans after he was substituted in the second half for his wonder goal, but Williams joked he wasn’t expecting a similar reaction had he been taken off.
“It’s a lovely touch, but I don’t think I’d have got the same reaction after the penalty! But credit where it was due, it was a fantastic goal.
“That was something else. It was either going to hit the corner flag or into the top corner - luckily for us it went in!”
And Williams said he was impressed with another of Dons’ new recruits, Samir Carruthers, who won the penalty for Dons.
He said: “We trained with him last week and I was really impressed with him. He seems a really good prospect and I’m glad he’s on our side.”