The US wrote the reports both times as “well done guys but this is not realistic for the following reasons”.
The Japanese proved them wrong some years later.
It’s not possible for the US to lose a conventional war they are ready for, just as it wasn’t possible for hamas to invade Israel.
But if either party takes their eyes of the ball and starts to listen to only what they want to hear, then anything is possible.
Don't be an armchair Admiral if you aren't sure why things are done in a certain way in the Navy. This was very publicized as a "failure", but the whole purpose of war-games is to learn new lessons. I would be embarrassed that you mistook this as a failure, and claimed we lost wars because of failures such as this one. The reason we lost recent wars is because there was no goal for those wars, so there was no way to win it. It was a political failure most of all. Vietnam, too. Without a goal, the most well trained militaries can't claim victory.