Yea I don't have the confidence that Bautista would be any closer to an average 1B defensively and I don't think he'd be better than EE.
EE has actually been improving defensively each year since becoming more or less a regular first basemen in 2012 and this year he actually put up a + UZR/150 for the first time in his career.
2012: 583 innings, -14.5 UZR/150
2013: 698 innings, -10.8 UZR/150
2014: 694 innings, -9.7 UZR/150
2015: 481 innings, +5.1 UZR/150
He's trending in the right direction at least, I think Bautista would start well behind him even if he is naturally a better defender.