Players who shine in the preseason can be anyone from an established veteran simply putting in the the work to an undrafted rookie free agent struggling to make the team. However, succcess in the preseason does not always guarantee equal success in the regular season, or even a roster spot.
Victor Cruz three seasons ago exploded in the preseason. In one memorable game against the Jets, he scored three touchdowsn and had 145 yards receving in the Giants' victory. Then he was almost cut. Regardless, Cruz only played in three games that season before breaking out in a huge way the following season.
NFL teams have 80 man rosters during the preseason, so there is not much play time to be spread around. As a result, it is the players who can make flashy plays that stand out. An offensive lineman is evaluated by a team during practice, not in the 20 or so snaps he may take during a game. However, one kick return can inspire a front office to retain a players services.
Due to those facts, this list will be offensive skill player heavy as those are the players who truly shine in the limited action of the preseason.