Garry Monk described his side’s form as one step forward, two steps back, following the Owls’ 5-3 defeat to Fulham at Craven Cottage on Saturday.
An Atdhe Nuhiu brace either side of Jacob Murphy’s strike was not enough to earn a result for Wednesday, leaving the manager frustrated.
Monk said: “It’s very frustrating, it was cheap defending for their goals.
“When we got back into it, it was schoolboy defending, which makes it frustrating with the clean sheets we’ve had recently.
“I believe there are players in the dressing room who can gain consistency. But they need to learn very quickly.
“The goals we are conceding are schoolboy, goals that should only happen sporadically for any team throughout a season, not consistently.
“We cannot work as hard as we do and go through it, taking a step forward but two steps back again.
“They are poor, poor goals. If you don’t make those errors you’re in better shape for a result. But in critical moments, when it’s a case of doing the basics, head that ball, clear your lines, we haven’t done it.
“We cost ourselves and that’s been too constant throughout the season and we’re a bit tired of it.”
Monk has already made the team aware of what he expects for the Owls’ final game against Middlesbrough on Wednesday evening.
He added: “I’ve said to the players at the end that we have to finish the season with three points, nothing less is acceptable.
“It’s about ending the season on a high and improving our home form. The need for three points must be there consistently.”