The Colts clearly went into the draft this year with a plan to improve the defense. They have done that so far, and they did it again in the fifth round, taking cornerback Marvell Tell out of USC. He gives them more depth at that position moving forward.
Tell was a mainstay in the USC backfield, playing significant time in all four of his years. He has pretty good cover skills as evidenced by his 13 career passes defended and his 5 career interceptions. That is the type of corner the Colts are looking for.
Getting someone who has played as much football as Tell has in the 5th round is a great value.