The former Premier League boss is preparing for his first season with the Hoops.
The Northern Irishman has recently been appointed as Ronny Deila's successor at Parkhead. And while there is currently plenty of optimism following the appointment, the Norwegian's tenure highlighted that the former Liverpool boss will have plenty to work on to take the club to the level they deserve to be.
And McGarvey believes that the area that is in most need of attention is the side's options at the back, with Efe Ambrose being singled out by the retired striker for criticism.
"The first thing he has to do though is sort out the defence. When you look at successful sides at any level of the game, a settled defence is the one thing that they all have in common," he told the Evening Times.
"He needs to get a settled back four or five that will play every week, rather than the situation we had last year where it was always being chopped and changed.
"Just look at the St Johnstone game at the end of the season, we're trying to win a game and the manager brings on Efe Ambrose. It pains me when I think of a Lisbon Lion like Jim Craig getting £65 a week when I played and then think of what guys like that will be getting."
Jozo Simunovic appears to be the best defender at Rodgers' disposal, but his season was largely defined by injuries so there will be question marks about how much he can be relied upon.
Meanwhile, Erik Sviatchenko and Charlie Mulgrew formed a promising partnership following the Dane's arrival during the January transfer window, but as McGarvey suggested, there appears to be a significant lack of depth with arguably only Dedryck Boyata also hinting that he has something to offer next season at the heart of the defence.
And while that may not be a problem in the Scottish Premiership as the Hoops will spend most of the time on the front foot anyway, it could be hugely detrimental to their chances of impressing in Europe.