Martin O'Neill has said his Sunderland squad lacks "real true ability" and that he has felt as though his team have been in a relegation battle throughout the course of the season.
O'Neill has invested significant sums on the likes of Steven Fletcher, Adam Johnson and Danny Graham over the last year, but Sunderland have been in the bottom half of the table since August and are on a run of six games without a win that has left them just six points clear of the drop zone.
The manager believes that, as a whole, the players at his disposal are not up to the required standard.
"It's been a tough season, but I knew that from August - I knew it was going to be a tough season for us," he said. "We tried to look at some things in January... I think we'd all felt it was going to be tough.
"You said this here about the top half of the table - and that's still possible. Win a couple of games and you can still do it, but the very fact is that it's been tough all year round, and if it's been tough all year round then that might be something to look at again.
"The season before that had been tough. We'd come in and staved off a relegation fight and I think... I think we need an improvement in the ability in the squad."
Sunday's game against Norwich at the Stadium of Light represents an opportunity to pull clear of danger, and O'Neill - who said he has "never felt like we've been out of" the relegation fight - feels that his players at least have the motivation required.
"Over the course of the season, we might lack a lot of things - we lack real true ability in the team - but I'm not so sure that I would always question the desire of the players," he told reporters. "I think that to get those points you have to show determination, you have to show that bit of fight in adversity. You really have to go and win some football matches.
"That's what it's all about and you can be forgiven an awful lot of things if you get a couple of victories and take it on from there I suppose. We have to win. We need improvement in ability in the squad - I think that much is obvious."
Even so, O'Neill feels Everton have shown that it is possible for teams to finish in the top six without major investment.
"There is absolutely no reason why Sunderland cannot be there," he said. "We are not a top-six team by any stretch of the imagination, but Sunderland is a top-six club in the making. I genuinely believe that and I'll believe that until the day I leave this earth."