That diagonal board on the gate serves a purpose, and its direction is important.
We have all seen that diagonal board that is usually found on the back side of the gate, it helps to hold the gate’s latch side up. Without the board the gate will sag, distort, miss the catch, and become troublesome. Having the board installed in the wrong direction is not much help, and will soon sag also.
While working on an exterior lighting problem in Roseville, CA, I saw a gate that was not closing as it should, so I took a photo.
In the photo the arrow points to the board that is incorrectly installed. The gate has been worked on several times so it is no surprise that it is not built right. The blue line is the direction that the board should be. With the board installed in the correct direction, the weight of the gate is held against the hinge side of the gate, which is secured to the building.
So if your gate is starting to sag, check that this board is installed correctly first. Then either fix it or call someone who knows how to do it.
That is your gate design lesson for the day. J