The Owls skipper admits that Paul Sturrock's men do not usually play as well as they can in the first 45 minutes of games, Tranmere being an exception of recent weeks.
Fans and Paul Sturrock have been critical of the club's showings before the break and Bullen knows that things must improve.
He told Footymad: "It’s about a whole mental attitude towards the game and sometimes we can get ourselves into a great position and then, it’s a horrible thing to say, but sometimes we can seem that we are going through the motions.
"Sometimes it’s not until we go a goal down and we have to give ourselves the kick up the backside and we realise we have to play the way we all know we can play – it happened against Blackpool and happened against Tranmere – we could have gone third on Saturday, the players were absolutely outstanding in the way they went about the warm up to the game.
"Now we have shown how well we can play we can’t drop those standards in the last few games of the season."
Wednesday's trip to Boundary Park sees Athletic in good form since former Millers boss Ronnie Moore took charge and Owls fan Luke Beckett joined on loan from city rivals United and Bullen knows they are a lot better than their league position suggests.
He says: "Oldham were half decent when they played us (at Hillsborough) – they scored late and we should have won, but they have shown that they have good players and they proved that by getting one hell of a result against Hull recently so it is going to be a hard, hard game but we don’t really need to worry about other teams – as long as we play with the tempo and aggression like we did against Tranmere, we should beat most teams, no problem about that."
As far as team news goes, Wednesday are down to their bare bones: Craig Rocastle, James Quinn and Matt Hamshaw returned to training during the week but it is doubtful whether they will take part or not.
Zigor Aranalde and Alex Bruce are suspended but Sturrock is sweating over the fitness of Richard Wood, who was taken off against Tranmere last week with a dead leg - the Owls boss believes that Wood's inclusion will not be confirmed until right before kick-off.