Big plays on offense and defense jump out. Most of the things we notice during an NFL game come on plays from scrimmage. That tends to be how it works in the preseason. In the second half of those games, a wide receiver who has 5 catches will stick out more than a guy on special teams with two tackles and a nice play to down a punt inside the 5 yard line. The truth is the second guy did more to earn himself a spot on the roster.
Putting up production at one's natural position is nice, but doing it against fringe players at the end of a preseason game does not mean a whole lot. It is a lot different from doing something against first stringers. The guys who play at the end of these games are usually developmental players. No matter how good they might look, they are generally not ready to make a big contribution, and their status on the depth chart even if they make a team will prevent them from even getting a chance.
The place where they can make an immediate impact is on special teams. Those are the roles bottom of the roster players can fill. They can provide a team immediate value. Either way, you are dealing with a developmental player. Most teams will take a slightly less refined guy who can provide some kind of value over the slightly more refined guy who can't. Again, the odds of bottom of the roster players seeing regular playing time from scrimmage are small and rely on the unlikely scenario of a team suffering an obscene number of injuries at a position.
So tonight and through the preseason, keep an eye on plays from scrimmage in the second half, but really focus on special teams. That is the true road to the roster for young, developmental players.