Sunderland midfielder Sebastian Larsson admits he is frustrated at the club's lack of consistency this season.
The Black Cats have endured a mixed campaign as despite sitting comfortably in mid-table, they have struggled to maintain their form and push on.
Unable to explain the reason behind their indifferent results, Larsson concedes it is tough to see the team not always fulfilling their potential on the pitch.
"It can be frustrating when we know what we're capable of, but then not perform," Larsson told the Journal. "We've had a good performance and feel really confident going into the next game, but for some reason we don't turn up on the day. For one thing it's not good enough and secondly it's frustrating when we know what we can do.
"To be honest, I don't know how many points we are away from the European places. I haven't been looking and I don't really know how many points we are away from the relegation zone either. However, I know what we're capable of.
"We've been way too inconsistent. We shouldn't have lost at Reading. We should be better than that. We've beaten teams like Manchester City this season so in a way it has been a good season for us, but I couldn't give you a good answer to why we are like this.
"The last ten or 12 games will determine what happens, and the league is very tight. We've got to look at it in a positive way and see if we can climb the table and finish higher than we did last year."
With Sunderland facing a trip to West Bromwich Albion on Saturday, Larsson is hopeful the club can once again reach their potential and claim victory over a side they have struggled against in recent seasons.
"They are a good solid side, but that's been the case for us all season," he said. "When we perform, we know we're a good side. As I said, we just haven't been consistent enough. We've been up and down in games with a great performance one week and not so good the next. That's been our Achilles' heel all season."