Trinity had shown promise for their National League North relegation fight with victories in their previous two matches, but fell apart.
Now Frecklington wants to bring in new defenders after labelling the goals against column embarrassing.
“We knew it was going to be a tough test, but when you defend like we did you are not going to get a (positive) result here,” he said.
“We had back-to-back victories (going in to the match), but went back to old mistakes and looked all over the place defensively. We were all at sea.
“It was the same people making the same mistakes. We don’t seem able to go five or six good games on the spin.
“I need to speak to the chairman to see if we can strengthen defensively, that is for sure.
“You can’t defend like we have done — and it is not the first time. We have put our faith and trust in certain players and certain players were making the same mistakes.”
Frecklington described the defending as Sunday League and not good enough to earn points.
“It was kamikaze defending, it was car crash.
“With the flair we have going forward — we hit the post twice, we created chances and we kept going to the end,
“But if you defend like we did you are not going to win football matches.
“We have had a long hard chat. You can do all the training in the world, but you can’t legislate for that.
“Bradford are a good side but we must have contributed to four of their goals.
“I would have been ashamed if that had been me out there defending like that.
“The goals against column is embarrassing.”
Determined Gainsborough Trinity boss Dave Frecklington believes his side’s heavy defeat at Leamington in January could prove to be a vital turning point.
Trinity, fighting for their lives in National League North, crashed 3-0 amid a poor performance.
The third consecutive loss left the Holy Blues deep in trouble in the relegation zone.
But the out-of-character performance was followed by two terrific victories over relegation rivals Alfreton and play-off chasing Chorley as Trinity looked more like a typical Frecklington side — one that works hard and is tough to beat.
“The Leamington game was turning point for us because that was a low blow,” said Frecklington.
“Since then we have worked hard and the boys deserve credit. It has been tough to find the right formation for the group
“We have improved the squad with quality throughout the season, but we went back to basics to what I know best.
“Players have got to work hard to make formations work though.”
Frecklington said the reaction to the Leamington loss could be as important as a heavy defeat at Chorley last season, after which Trinity fought back to escape relegation.
He also praised returning defender Brad Beatson and keeper Henrich Ravas for their roles in helping the turnaround.
“Brad looks a totally different player, perhaps because he has a point to prove after things did not work out at Boston for him,” said Frecklington.
Ravas’ loan from Derby County has been extended by a further month.
Frecklington was speaking before the postponement of Saturday’s match at Curzon Ashton due to a waterlogged pitch.