Consistent individual play during the preseason creates trust between players and coaches. If certain players, game after game, continually make game-altering plays that push their team towards victory, coaches will have reason to believe that those players can do the same during the regular season.
At the same time, every game is different, and consistent high-level play is very difficult in the NFL. It only takes one poor performance for coaches to change their minds about where a player lies on the depth chart or if they even deserve a roster spot at all.
The performances of many players on Thursday versus the Packers will be a good indicator as to whether they play with the starters or backups in the following preseason games and eventually, the regular season.