Marc-Antoine Fortune grabbed the only goal to hand the visitors the points but Johnson was frustrated by a handball claim in the build up.
He said: "Our cup finals are the six or seven teams down the bottom with us, starting with Doncaster next Friday.
"We play very well against the top teams, have as much possession and as many opportunities as them, but we never turn those chances into goals and wins.
"We don't dominate when it comes to corners or set plays, and our quality wasn't there. We arrived either too late or too early and I'm disappointed with that.
"I'm not burying my head in the sand because I thought the boys worked hard and gave everything. I love them for that.
"The lads were saying there was a handball in the build-up to the goal but we just don't get the 50/50s.
"Not only were Wigan stopping our momentum but the officials also stopped our momentum. They allowed them to take their time over everything when we were in the ascendancy."
- Sports & Recreation