The Colts have a bunch of rookies on this team. They had 10 draft picks alone. Not all of those draft picks have seen the field, but the ones that have have done a decent job. Most of those rookies play on the defensive side of the ball.
Rock Ya-Sin is the only rookie who starts. He is the corner opposite of Pierre Desir. He has had an up and down start to the season. He got beat badly in Los Angeles for a touchdown, but played better last week. Ya-Sin will get better as the season goes along as well.