Ibrox side Glasgow Rangers were in fine form last season, but could be tested more defensively in the Scottish Premiership.
Rangers have added the likes of Clint Hill and Lee Hodson this summer, with Mark Warburton’s side attempting to strengthen their backline.
However, Walker feels that there is more work to be done, if Rangers are to challenge Celtic.
“I can see Rangers having more strength and intensity than last season and the signings of Barton and Kranjcar should give them a little swagger and arrogance that all top teams need,” the Sky Sports pundit suggested.
“With Martyn Waghorn and Barrie Mackay sure to be prominent players for Rangers, I have no doubt the Ibrox men will score goals regularly but defensively they have to improve enormously.”
Walker then went on to single out James Tavernier for criticism.
He added: “James Tavernier catches plenty of headlines for his extraordinary goalscoring from right back but as he showed in the Scottish Cup final against Hibs, he can be very weak at defending. All three goals scored by Hibs were so soft from a Rangers point of view and it`s their biggest weakness.”
Tavernier was a revelation last term for Rangers, as his attacking instincts saw him score 15 goals from right-back.
Tavernier is likely to be tested far more often defensively this campaign, but he looks likely to remain as a starting player in Rangers’ line-up.
Rangers have also brought in a great deal of attacking quality this summer, with the likes of Joe Dodoo and Niko Kranjcar arriving.
Rangers have won their first four competitive matches this term, and they kick off their league campaign with a match against Hamilton at the weekend.