I get it. The AB Fence panel from post to post is straight and you cannot bend a concrete block. So, the AB Fence System was designed to create curves by having a little wiggle room at the connection of the panel and post. As the panel block fits into the groove the AB Fence post block there is enough room to angle the block to create a bend.
Read more about AB Fence Curves and other installation tips at www.allanblock.com.