Listen to Jawge, he is a man who definitely knows what he is talking about... I know that whenever I was picking out red oak boards for bows, the front grain would look "straight enough" and I would think it would make a bow only to have it blow up on my tillering tree. I started checking side grain and have had far fewer failures. The front grain tricks me into thinking it will be ok, the side grain never lies...
That is what I was trying to convey when I drew the pictures, sorry they weren't all that great I was at work and trying to draw them fast in between patients.