Liverpool have been on a poor run of form, which has seen them go on a run of three league games without a win, including losing their last one against Southampton.
The Reds have dropped down to second in the league table, allowing Manchester United to occupy top spot in the league standings ahead of their clash at Anfield on Sunday.
Whelan conceded that a number of players have not been doing what they were when Liverpool were flying high and their performances levels have gone down.
He stressed that Liverpool’s form cannot be termed as a crisis yet, but he admits that the big players will need to hit their high standards again in order to get the side moving again in the right direction.
The former Red said on LFC TV: “The form of a lot of the major players has dropped below the tremendously high levels of football they were playing.
“I am talking about Robbo at left-back – the crosses aren’t the same, Trent at right back – the crosses aren’t the same. We are not getting the same amount of good balls into the box.
“The front three are not scoring or creating as much as they were.
“We are getting into an awful lot of good positions in the final third of the pitch and the final pass is going astray or there is a mis-control inside the box.
“These things have all added to the reason why Manchester United are ahead of us now.
“At the moment it is not a crisis, we have lost a couple of games and drawn a couple of games, but so what?
“It’s a long season, but we have to get back to the standards we have set over the last couple of years and if we do, we will be back on top again very soon.”
Liverpool have not lost a league game at Anfield since April 2017, but head into the clash on Sunday with a serious defensive injury crisis.