Dagnall, 26, clipped home his fourth goal in as many matches in Tuesday night's 2-0 home win over Millwall to take his tally for the season to six and has done as much as anyone to help maintain the club's momentum in recent weeks.
The Liverpool-born forward has not had an easy time of it since arriving at Barnsley from Scunthorpe in January last year and was loaned out to Bradford at the end of last season.
"I've known Daggers a long time and I've got a great friendship with him," said Flitcroft, who worked with Dagnall previously at their time together at Rochdale. "I love the fella to bits and I was never going to give up on him.
"I'm sure the fans did, for sure. If you tell someone for long enough that they can't do something, they're going to believe it and I heard a lot of that.
"But he will work. When we first signed him I thought he's coming to a tough hard-working town here and Daggers will be appreciated and I was surprised when he wasn't. But he is now.
"He's getting his reward. He's not doing anything different. He's working the same, he's always worked hard and the finish (against Millwall) was exquisite, as good as you'll see on a football pitch.
"He'll lead that attack. He's a grafter."