I watched the goal again, and the only players I couldn't find any fault with were Bale, Moore, James & Davies. Everybody else did something that was less than optimal, while Croatia did the opposite and put together an excellent counter-attack from the turnover. It was just a bad day at the office, and the players need to analyze the video before having a good chat about it. I don't know if Wales have a defensive coach, but if they haven't got one then they should look into it.
PS This is my final contribution to this well-balanced and thoughtful debate