I don't see how one can get super excited over a prospect during preseason games and ignore the rest of the team when they play awful. To accept that they're meaningful to a certain group and not another is simply making excuses for deficiencies.
I think these games at the very least are indicators of the raw talent and focus of each individual player at that time. I'm particularly interested in the focus because if it's low that just means it will take more time at the beginning of the season for them to catch up - if they catch up at all. As we all know, every game in the season is meaningful when it comes to making the playoffs.