True but Millar is still off to a decent start. He has a higher Avg, much higher OBP and only 2 less RBI's than Mientkiewicz. I'll still take Millar over a full season despite his inferior fielding. Mientkiewicz is just not that good of a hitter. With Millar you know you're gonna get around .280 20 HR's and 80 RBI's.
That being said I would look for the Sox to upgrade 1B in the offseason with a guy like Paul Konerko. I'm not sure who else will be on the FA market but his name jumped out at me. It also depends on how the Damon situation plays out.