It is now three straight defeats for Barnsley after they were crushed 5-1 at home to Watford on Saturday.
The Reds are now second bottom with four points from eight games in which they have conceded 22 goals.
The match began frantically with three goals in the first 17 minutes. Troy Deeney fired the Hornets ahead after Barnsley thought the striker was offside.
Jason Scotland got his first goal of the season on his first start when he levelled six minutes later after robbing Iriney of the ball then firing in from 15 yards.
But the Reds were level for just two minutes as Davide Faraoni tapped home a deflected cross by Lewis McGugan to make it 2-1.
The fourth goal was always going to be crucial and Watford got it just before half-time when Deeney played Ikechi Anya in down the left of the box and he powered past Wiseman before setting up Fernando Forestieri to make it 3-1 with a tap in.
Barnsley were better in the first half and Manuel Almunia had to make a phenomenal one-handed save to deny Martin Cranie's header from four yards out.
But Sean Murray finished the Reds off when he fired into the bottom left corner with an excellent 25-yard strike.
Anya then made it five on 79 minutes when he tackled David Perkins on the edge of the Watford box following a Barnsley corner and sprinted the length of the pitch before firing in.