Disappointed Grimsby Town boss Russell Slade criticised his side’s defending after they were thumped 4-1 by Mansfield.
A brace from skipper Krystian Pearce and two Lee Angol penalties helped Stags wrap up their first win in four attempts.
Grimsby pulled a consolation goal back when Sam Jones scored the third penalty of the game with five minutes to go.
But there was no disguising the fact that they were well beaten following a toothless display,
Slade said: “I’m very disappointed with the performance today.
“Particularly because of the way we conceded the goals. We were very milky in terms of defending.
“They’ve not really undone us in open play. Their goals came from a free-kick and corner and two penalties.
“You have to value the basics, defend properly and do your job but we’ve not done that.
“There was probably three or four free-kicks we gave away outside our box and we can’t keep doing that.
“We can’t keep inviting them to launch the ball into our area. In the end they’ve scored from one of those situations.
“Some of our build-up play was decent but we just didn’t have that ruthlessness to get the goal.”
Mansfield took the lead when Angol scored a 34th minute spot-kick after David Mirfin had been upended by Mills.
Scott Vernon and Siriki Dembele wasted chances to pull Grimsby level just after the restart.
And they were made to pay for it as Mansfield doubled their lead on 54 minutes when skipper Krystian Pearce volleyed home.
The points were safe six minutes later when Pearce prodded in a rebound after McKeown had pulled off a superb save to deny Rhys Bennett.
Stags made it four when Angol scored from the spot on 79 minutes after he had been brought down.
Jones pulled one back for the visitors after Bennett fouled Diallang Jaiyesim.