Goals from Andy Cook and Isaiah Osbourne saw the Saddlers hold a 2-0 lead with just 10 minutes to play at the Banks’s Stadium on Saturday.
But a Luke Leahy own-goal gave The Chairboys hope they could secure an unlikely point.
And while Walsall made it 3-1 moments later through a Dominic Gape own-goal, they then conceded again in the 90th minute to set up a tense finale.
“We know we should have been out of sight,” Ferrier said. “We were 2-0 up with 10 minutes to play.
“At the end, I feel we were a bit complacent.
“And the gaffer had a go at us after because of that.
“We need to be better at seeing games out. But we got the three points which is the main thing. We had been on a sticky road so it was important we got the win.”
After an impressive start to the season, Walsall entered the clash with Wycombe have fallen to back-to-back defeats at Luton and Southend.
But while he was disappointed with the closing stages of the game, Ferrier felt – overall – the Saddlers showed they beginning to recapture their best form.
“We have to play at a high intensity,” the striker continued.
“I feel like in the last few games, that is where we have let ourselves down.
“We knew we had to get back to what we were doing at the start of the season.
“We were causing teams all sorts of problems with the way we play.
“The gaffer was drumming that into us all week.
“He wanted us to get back to what we can do and what we are best at.
“Against Wycombe we did play with that intensity.
“You could see everyone putting their bodies on the line, blocking balls.
“Of course the defenders, the entire team, want to keep clean sheets.
“But I feel after the run we’d been on, the most important thing was getting the three points.”