STEVE Lomas described his side's defending as "not good enough for this level" after Millwall were beaten 3-2 by Blackburn Rovers.
The Lions have now conceded three-or-more goals in no less than six away fixtures this season and were once again undone by a set piece at Ewood Park.
Jordan Rhodes scored the opener after a slip by Mark Beevers before an unmarked Ben Marshall headed in a simple cross after ghosting in behind Paul Robinson.
Rovers' third, scored by David Dunn, came after Millwall twice failed to clear a corner and meant goals from Martyn Waghorn and Steve Morison counted for nothing.
Lomas said: "We were the masters of our own downfall and have to look at ourselves. The three goals that we conceded weren't even schoolboy - probably more like U12s - and that's the reason we are looking down rather than up.
"Going forward we are a threat and scoring goals, but all season we've given away absolutely cheap, cheap goals and again that's raised its ugly head.
"We've scored two goals away from home and should be coming away with at least a point, but we are not and that's just criminal.
"I cannot keep saying we were unlucky and we are going to have to do something about it. This was a ripe opportunity to get three points.
"It's about having desire in the box. If you don't get a head on it, you've got to ensure the guy you are marking doesn't get a free header - at the very least he's heading your head and has a nasty cut on his face, or a broken nose.
"I didn't see Morison or Waghorn being given many free headers in the other box, and that was the difference today. It's not good enough for this level.
"They have all been given roles and responsibilities, we work on it in training but ultimately when they are out there they have to deal with corners and crosses themselves.
"If this wasn't a reoccurring theme you could say it was just one of those days, but it is a reoccurring theme and the reason we are where we are in the league.
"It's about wanting to get hurt and putting your body on the line. I saw that in Blackburn's two centre halves. If they bang one in from 35 yards, or cut us open with a passing move, you hold your hands up and say 'well played', but they didn't do that - it was just too easy."
Lomas was once again left to rue controversial decisions which he felt contributed to Millwall's defeat.
In the first period, Morison should have won a penalty when he was tripped from behind, while Alan Dunne was caught by a studs-up challenge, and subsequently stretchered off, moments before Blackburn went 3-1 ahead.
"I'll phone [referees' assessor] Dave Ellis again for the 15th apology of the season I'm sure," Lomas added.
"What can you say? It is every week, every week it is blatant, game-changing decisions and we're on the end of quite a few. The penalty is so blatant it is frightening.
"Alan is fine - he has a bad gash on his knee. It was a very poor tackle."