The Reds now face the prospect of finishing the season behind Everton.
Scales told talkSPORT: "The players that have come in haven't performed well enough or consistently enough. They have shown that they have the quality but they have to be consistent for 90 minutes game in game out, especially when you are playing for a club like Liverpool.
"New players that come in want to be part of something fresh and new and hit the ground running. If they don't then confidence is a fragile thing and I think that has proven the case.
"They have risen to the challenge in some of the big games and cup games have been exactly that but consistency wise it hasn't been there and Kenny will demand much more of those players and certainly he will have to change one or two things in the summer."