A 1-0 defeat at Ibrox against Celtic on Sunday means Rangers are already four points behind the reigning Scottish champions in the league table.
Rangers have not looked convincing at the start of the season and their new signings are yet to have the desired impact on their style of football or results.
Walker pointed out that Rangers have already played a number of games this season and indicated that the sample size is big enough to gauge the quality of their squad.
He feels the worrying thing is that Rangers look like dropping more points going forward and with two out of the next three derbies at Parkhead, the former Scotland star does not see the Gers making up the gap with Celtic.
Walker said on the Go Radio Football Show: “Rangers have played a lot of games.
“They have had qualifiers, cup games and league games and they are already four points behind after four games.
“If you are a Rangers fan it has to be a big concern because I can see Rangers dropping more points.
“You have now got three Old Firm games and two of them are at Parkhead.
“I don’t see Rangers making up the gap.”
Rangers will be desperate to get back to winning ways when they take on St. Johnstone after the international break.
