Let me explain a few things about logs/ lumber in general. The "pith' that runs through the center of a tree is to be avoided. Why? Because it tends to be either hollow, crooked, pithy, or frought with all sorts of defects and problems.
When a round log dries, the log dries from the outside in. In other words, it will split radially, from the center to the outside edge. When a piece of lumber is "center cut", the pith or center of the tree is wandering to and fro inside this board. It will split everytime from the pith to the nearest exposed edge. This edge might be on one side for the first foot or two, then switch sides and split towards another edge. The resulting split is where the wood will dry out faster, the wood there will shrink and warp.
Sure, you can cut a big, wide board out of the center of a tree, but you won't be able to use it's entire width (not for anything nice, anyway). So, it's best to figure on loosing the wood closest to the center.
You need to avoid uneven drying. This is why you try to seal the ends of freshly cut boards. As soon as a crack appears, it allows the wood on either side of the crack to dry faster, making the crack run, which just leads to bigger cracks, warp, and loss of useable material.
Any knot in the surface of a board, or where a branch was cut, is really end grain, and will allow moisture to leave the wood unevenly. Wavy sufaces will result. Unfortunately, This is where a lot of wood's "figure" comes from- proximity to a branch, swell, burl, or root. So the more figure a piece of wood has, the harder it is to dry without loosing useable material.
