I checked out the pattern andit would appear that the seams must match for the design to be effective. I'm not sure it is just "squaring up the block". However, try it without cutting the block to see what the effect would be if you did square to the smallest.
A pattern like this, although appearing simple, must have accuracy in piecing the various sections. The side of the square in the corners of the square blocks must alighn with the triangles in the snowball block. Without them meeting you don't have the continuous "twist" effect.
Having said all that.....Go back and look at your piecing to see what have happened to cause them not to end up the correct size. Was it in cutting or piecing. Before attempting to square you need to find out why they didn't end up the same.