The loss ends the Wildcats season with a record of 15-6-2, while the Saints move on the quarterfinals of the national tournament and will take on either No. 5 Rio Grande (Ohio) or No. 12 Embry-Riddle (Fla.), Wednesday at 11 a.m.
The Saints improved to 15-4-1 on the season and avenged a 2-1 overtime loss to the Wildcats in the 2013 season opener back on Aug. 24 at Ashford.
Krauthheim opened up the scoring for Ashford in the 30th minute with a goal to put AU up 1-0. Daniel Dreier put the Saints up 2-0 in the 67th minute off an assist from Lucas Almeida.
With their back against the wall, Jordan Thacker kept Baker in it with a goal in the 73rd minute and then Austin Shiney tied things up in the 84th minute for BU to send the match to overtime.
Ashford outshot Baker, 26-14, and Bickley had a stellar 14 saves, while Chris Higgins had five saves.
Seniors Ben Coyle and Andy Griffin led Baker in shots taken with three in their final game as a Wildcat.