All of the £105m spent by Dalglish since he returned in January has gone on strikers and midfielders and Evans feels his old pal needs to use a few quid on the back four.
"I do feel they're going to need a little bit of cover in defence," he told radio station talkSPORT.
"Daniel Agger is a great footballer, but obviously injury-prone, and Jamie Carragher is still the lynchpin.
"He gives so much information to the players around him and the two young lads, [Martin] Kelly and [John] Flanagan. Carragher helps them an awful lot and he'll be the biggest loss when he goes.
"I do feel we need to find a centre-back, as we seem a bit short at the back, and that's a worry."