Whereas the Trotters pitched up at Hillsborough on the back of three straight wins, their hosts had one in six League One games.
The Owls played three central defenders for the first time this season, a system manager Darren Moore said they only started working on from Thursday.
At the end of an unconvincing first half they lost league debutant centre-back Lewis Gibson and experienced midfielder Sam Hutchinson to injury, prompting a change of system, but won with a Lee Gregory goal and a first clean sheet in seven matches.
“It was a hard-fought win,” said centre-back Iorfa. “Bolton played some good stuff and we dug in together, stuck to the task and got a good result and a clean sheet as well – something we can build on.
“When you’ve got two guys coming off you’ve got to deal with the adversity and we did it really well. Not every game’s going to be pretty. We’re going to get a lot of games like that where people come here and make things difficult. We know we can play a lot better but there’s a lot of positives to take.”
Iorfa claimed Bolton put pressure on referee David Rock at half-time, unhappy the centre-back did not add to a 28th-minute yellow card for a foul on Michael Williams when he overran a ball he brought out of defence.
“Kieran Lee tripped over and he ran into me, there was nothing I could do,” he said of the foul given against him just before half-time. “But if I was in their shoes I’d be doing the same thing.
“It was never a red card. The referee used his commonsense. In the tunnel a lot was said to him but he wasn’t having any of it.”
Details of the extent or even nature of the half-time injuries were scant, with Moore suggesting they could be muscle problems.
Owls report: Page 3