Baines was superb at the DW for Saturday's 2-2 draw.
"He's an excellent player - without a doubt the best left-back in the league," Caldwell told the Wigan Post. "He's up and down, he provides great quality in an attacking sense and he gets back and provides cover for his defenders.
"He's the one player in their team you would target. When you look at their team and the left-back is their most attacking player, that shows you he must be doing something right.
"At this moment in time, he's the best. He's back in the England team, he played the last game with Ashley Cole being out, and he's pushing for that place again. Him and Steven Pienaar have had a great relationship for some time. They are Everton's main attacking threat."