Ricardo Fuller put the hosts in front but Wednesday should have at least been level by the break, with lone striker Connor Wickham a constant danger.
But when midfielder Dan Gosling doubled Blackpool’s advantage midway through the second half, Wednesday’s heads visibly dropped.
That prompted an angry outburst from centre-half Johnson after the game.
He said Jones would be blamed for the defeat – and the subsequent sacking, which was announced 24 hours later, confirmed that – but insisted the players must shoulder the blame.
“We went a goal down, which was an individual error, but we bounced back and should have gone in at least 1-1 if not 2-1 up,” said Johnson.
“As the game went on, we just melted. It felt like we just gave up. It’s not good enough.
“Blackpool had a good spell in the second half, and after that if just felt like there was nothing. The lads gave up. The second goal was another mistake, people not doing their jobs. It’s killing us at the minute.
“It’s tough, so frustrating.”
The Owls made the worst possible start when Fuller flicked the ball home from a near-post corner by Thomas Ince after just six minutes.
Jeremy Helan spurned a great chance to level almost immediately. Wickham raced down the right and pulled the ball back to the Owls midfielder, but somehow he contrived to fire wide with the goal at his mercy.
Wickham, the on-loan Sunderland striker, was looking dangerous as a lone forward – Matty Fryatt was a substitute although Jones planned to extend his loan deal from Hull City after it expired following Saturday’s game – and he forced goalkeeper Matthew Gilks into a good save.
The England Under-21 striker raced clear of Blackpool’s defence, but his hard, low drive was straight at Gilks and the chance was gone.
Jose Semedo also headed wide from Roger Johnson’s right-wing cross as the recalled Jaques Maghoma showed enough quality to suggest he can make an impact at Championship level after his summer arrival from League Two Burton Albion.
Wickham was having his best game in a Wednesday shirt and he once more turned supplier to create a golden chance for Semedo.
With home fans on their feet demanding a penalty after a collision in the visitors’ area, Wickham raced down the right and his cross picked out Semedo, who mis-kicked with an equaliser beckoning.
The game became stretched in the second half, going from end to end, with the mercurial Ince a constant danger before Gosling fired home the crucial second goal.
Left-back Tyler Blackett – on loan from Manchester United – broke down the left and pulled the ball back for Gosling, who side-footed home from 10 yards out to seal the victory.
Wednesday are the only club in the Football League yet to keep a single clean sheet, and Johnson – who has the unwanted record of relegation in the last three seasons with Birmingham City and Wolves – said: “It’s disgraceful. Normally you can scrap out a 0-0. It isn’t good enough and everybody has got to hold their hands up.”
Before his departure, Jones had moved to strengthen his defence by signing Dutch centre-half Glenn Loovens, a free agent after leaving Spanish club Real Zaragoza.
The 30-year-old former Celtic stopper partnered Johnson in defence at Cardiff City under Jones, and could make his debut tomorrow against Leicester City after failing to obtain international clearance ahead of Saturday.
“Glenn has played for some great clubs and is experienced,” said Johnson. “I played with him at Cardiff and we had a great partnership.
“If we could recreate the form we have had in the past that would be good. He’s a good player.”
Loovens has been training with the Owls for a while, playing in a behind-closed-doors friendly last week, and Jones is a big fan.
“He has quality, composure and a bit of experience,” said the Owls manager on Saturday night. he also revealed Reda Johnson and Michail Antonio missed the defeat due to injury.
Jones had planned to hold talks with Hull City manager Steve Bruce today in an attempt to extend Fryatt’s loan deal for a third month.
Paul Ince returned to the Bloomfield Road dugout on the back of his five-match stadium ban and said they had “disrespected” the Owls in the first half, prompting half-time changes.
He said: “We got the early goal which I wanted. We worked on that set piece.
“We thought we were going to go and get two or three but the problem was we thought it’d be easy but it wasn’t.
“They had two or three good chances and I’ve been down there when you’re struggling. You create good chances and I feel for Dave Jones.
“I had a go at the lads at half-time.
“We disrespected Sheffield Wednesday but we were brilliant in the second half,” explained Ince.
“We had lots of chances and looked a better team.
“It’s great to be back and even better with three points,” said the former Blackburn Rovers manager.
“You don’t realise how much you miss it. Five games is a long time. I was concerned if we’d got beat it would be my fault. Alex Rae and Steve Thompson have done a fine job.
“I wasn’t sure whether to sit in the stands or the touchline and I was glad I did (the latter).”