The Storm were horrible early in Saturday's match, with their completion rate sitting at just five of 12 as the Sea Eagles scored the opening two tries to race out to a 14-0 lead.
But it was all one way traffic from that point on, with Melbourne piling on six unanswered tries either side of halftime to turn the contest on its head.
Manly's fifth loss on the trot leaves their finals hopes on life support.
Foran's men now nurse a 9-11 record, meaning they will have to win their last four games to have a legitimate chance of making finals.
In a further blow for the Sea Eagles, prop Taniela Paseka limped off in the first half after suffering a suspected MCL injury.
With so much to play for, Foran was at a loss to explain why his team lacked a hard edge.
"We can't explain it. I just don't feel that there's a real hard edge about our approach to our footy at the moment," he said.
"You know, 14-0 up, you should be in control of that game of footy. You should be able to put the foot on the throat and maintain a level of control.
"I feel very, very sorry to our fans. We had a lot to play for today. There was a lot on the line. There was good reason to turn up and put in a really good performance. And after about the half an hour mark, that just wasn't good enough.
"I had a bit to say (to the players) just before, but I'll keep most of it in house."
The Storm snapped a three-game losing streak, but at 9-12 they need to win their remaining three games and rely on other results to go their way in order to sneak into the post-season.
Fittingly, Melbourne's Nick Meaney was a perfect nine-of-nine with the boot in a place he will soon call home.
The centre will join Perth next season and there were plenty of Bears fans in attendance to watch their future star.
Perth coach Mal Meninga led around 1000 supporters on a pre-match 'Bear Walk' in the rain to HBF Park to signify the venue will soon become a 'Bear Pit'.
The NRL's newest franchise launched their home jersey on Friday, with the red-and-black hooped strip paying tribute to the first-ever North Sydney Bears side of 1908, when the club was a foundation member of the NSW Rugby Football League.
Saturday's match started brilliantly for Manly, with Brandon Wakeham and Tolutau Koula touching down inside 26 minutes.
But the Storm caught fire in the final six minutes of the half in what proved to be the turning point of the contest.
Sualauvi Faalogo's perfectly-weighted chip allowed Tyran Wishart to run onto the ball to score in the rain.
And the margin was whittled back to just two points by halftime when Hayden Watson scored his first NRL try by weaving through two gaps to touch down.
The second half resembled a training drill at times for the Storm as Oryn Keeley, Faalogo, Moses Leo and Siulagi Tuimalatu-Brown all found cracks in a leaky Sea Eagles defence.
Manly weren't able to hit back until Blake Wilson crossed with less than three minutes remaining, but it was a hollow try on a dark day for the Sydneysiders.
