Both were prominent in the early stages when the Seagulls' smart play indicated a hard afternoon for the home club.
Ward, signed a couple of days ago from Wolves on a season's loan, was involved in setting up several promising attacks which put Birmingham's reconstructed defence under pressure.
But Agustien was the player who created the breakthrough in the 73rd minute. He put a pass into the path of Crofts who scored with a low measured cross shot to the right of Randolph.
More top news
Surrey Heath MP Michael Gove has confirmed he will stand for leadership of the Conservative party - taking on Maidenhead MP Theresa May
Thursday night's weather for the west of the region
Thursday night's weather for the east of the region