in fact there was a third Jedi , a padawan as well but i do not remember her name. then Deviss was a Commander, not a Lt.
some other info:
-Deviss was a scout troop, and he was also a great sniper.
-the troopers that had the Commander Rank on the left were superior troops, so at least Lt's. the other were just simple troops.
-Barris and the other padawan were sent in a scout mission similar to the one on Geonosis (Barris and Ahsoka on Geonosis)
-at order 66 Barris and the other padawan were killed by Deviss and Bly which hurried to catch them.
pretty good topic