Rondon was the Baggies' marquee summer signing, with the club playing a sizeable fee to snap him up from Zenit St Petersburg.
The powerful forward did score the winner in West Brom's latest match against Norwich City, but Nicholas still has some doubts over the Venezuelan international.
"Rondon, what is he actually bringing to the team," Nicholas questioned. "I think he's strong, he's quick, but the rest of the team are having to make 20, 30 yards to get up to him. By that time he's probably lost the ball.
"He's technically okay, he's not brilliant, but he has to hold on to it for longer. It just comes back off him. They can't make up the ground."
Rondon has had a stop-start opening to his time at West Brom, with his international commitments hampering his progress.
The target-man has had to travel to South America twice since signing, and he is yet to get into the groove at the Hawthorns.
Rondon has only managed to score twice in his first 11 appearances so far for the Albion, but Tony Pulis will hope that he kicks on after his latest strike against Norwich.
West Brom have struggled for goals over the opening of the campaign, but they have still made a reasonably encouraging start - and sit in 10th place in the Premier League table.