Johnson, who made three changes at Rochdale, said: “You can have all the excuses in the world, we all know what they are, but we didn’t do enough.
“I thought two or three went under mentally, which I’ll keep in house, but I’ll have a word with them.
“I just thought we lacked what we’ve normally got which is that bit of quality and that bit of energy. I’m not saying that as an excuse from the other day, I’m just saying that as a fact.
“I am not worried because when it goes from Saturday to Saturday, we’ll have a lot more time to get working with the players. I was a bit disappointed in a couple for different reasons but that’s life. I don’t regret the changes because I wanted to show trust in the squad. I think the players will regret their performance.”
Rochdale cruised to a convincing victory.
The Reds were lacklustre throughout, leaving former Reds chief Keith Hill’s men to pounce.
Barnsley conceded after eight minutes when Donal McDermott flicked the ball into Calvin Andrew’s path, and he fired home from 20 yards.
A simple set-piece handed Rochdale a two-goal lead in the 36th minute when Peter Vincenti planted home a header from McDermott’s inswinging corner.
They fell three behind in the 63rd minute when Ian Henderson clipped in a shot and it could have been more.
Rochdale: Lillis, Rafferty, McNulty, Lancashire, Kennedy, Allen, Henderson, McDermott (Noble-Lazarus 84), Cannon, Vincenti (Bunney 75), Andrew. Unused substitutes: Eastham, Alessandra, Collis, Rose, Camps.
Barnsley: Davies, Wabara, Roberts, Mawson, Nyatanga (Smith 65), Harris, Pearson, Hourihane, Rothwell (Crowley 46), Wilkinson (Winnall 46), Watkins. Unused substitutes: Walton, Scowen, Maris, Digby.
Referee: G Sutton (Lincs).
Man of the match: Jamie Allen.