David Moyes fears Everton's transfer problems could undermine their pursuit of Champions League qualification but refused to discuss the ramifications for his own future at Goodison Park.

The Everton manager, who is out of contract in the summer, admits his squad has shown the ability and consistency to remain in contention for a top-four finish but believes it could be exposed by the lack of January additions.

Moyes wanted proven talent that could instantly strengthen his midfield or attack but an £8.6m move for the Dutch international Leroy Fer collapsed amid concern at his recovery from a recent knee injury and Everton were unable to match Sevilla's asking price for the striker Alvaro Negredo. He then instigated an alternative plan to bring in young talent for the future, signing the Barnsley defender John Stones for £3m and inquiring about the goalkeeper Jack Butland before his move to Stoke City.

The Everton manager said last year he would delay negotiations on a new contract with the chairman, Bill Kenwright, until after the January window. But, asked what impact the transfer frustrations would have on his position, Moyes said: "I wouldn't discuss my contract. We are just one day through the window and it's not the right time. But we are concerned we didn't add to the squad because we know we needed something extra.

"It wasn't for the want of trying, though. We didn't go scattergun at the end when we didn't get Leroy Fer but we tried to add some good players who would make a difference to the first team. And, if that didn't happen, we looked at bringing in young players who could be ones for the future and add value. We are disappointed obviously. Fer is a top player and it's a shame it turned out like that, but we are still one of the contenders to be in the top half and in and around the top four."

Moyes believed Everton lacked depth before January but the squad is lighter after the close of the window, with Stones the only addition and Ross Barkley plus Magaye Gueye leaving on loan. "We are short," he added. "We said before the window opened that we're short of what we want and we tried. But it didn't happen and that's the situation we have to deal with. For different reasons it didn't work out but it wasn't for the want of trying. If there is any criticism then maybe we could have tried a little bit earlier."

The Everton manager would not divulge why the club made its big money moves late in the window. "I couldn't quite give you the answer to that," he admitted. "I wouldn't say that [the money wasn't made available until late]."

Everton do have Kevin Mirallas and Darron Gibson playing again after lengthy injury lay-offs and entertain Aston Villa on Saturday one point behind Tottenham in fourth. And Moyes admits Everton have found the consistency to sustain their challenge, injury and fatigue permitting.

He said: "I would say we are one of the contenders for the top four, for sure. It's a question of keeping at what we're doing. The chairman and the chief exec were both on record as saying we didn't have much money to spend, so no one could be surprised, but at least we tried to give it a go. Now we have to deal with where we are.

"Maybe where Everton finish is where Everton are as a club. I spoke about the need to get off to a better start and we've done that. The top clubs have that ability to maintain it over an entire season, but perhaps we don't. One thing I would say, though, is that we've shown incredible consistency in our results. We don't lose too many even if we are not quite there. There is disappointment [over transfers] but it doesn't alter how this team has been playing and what this team has been doing."