West Ham United have conceded just two goals in their last six matches.
Nicholas feels that West Ham don’t have the defensive reinforcements that some of their rivals for the European spots do, and they can look vulnerable at the back.
The former Scotland international argues that James Tomkins’ inclusion at right back proves that West Ham are weak in defence, but he has not ruled out their chances of making it into the top four this season.
"The problem for me is still at the back," he said. "They are still a bit vulnerable at the back, even though their goalkeeper is very good.
"Perhaps that is because of the injury situation, with James Tomkins having to play right back.
"There’s still a good feel about West Ham though. We will be talking about the top four for them soon."
Tomkins has actually looked very accomplished during his time at right back, and seems to have established his place in the team ahead of Carl Jenkinson.
The 26-year-old is used to being deployed as a centre back, but he has thrived in his role on the right hand side of the defence.
And, despite Nicholas’ concerns, West Ham’s defensive record has actually been very eye catching of late.
Slaven Bilic has tightened things up, with many of his attacking players on the treatment table, and the Hammers have let in just two goals in their last six outings.