Zach Kerr was one of the players that some Colts fans (like Stephen Reed) were hoping to see scroll across the bottom of the screen during the 7th round of the NFL draft. But it didn't happen. The Colts, however, had been in touch with him and said, "if nothing happens [i.e., you don't get drafted], keep us in mind." The next day, Kerr was an Indianapolis Colt.
He comes to Indy with a chip on his shoulder. He wants to prove that he can play. He came to town with the intention of picking Robert Mathis' brain--he wants to learn and wants to improve. He wants to show the NFL that he isn't just some undrafted guy.
Early reports are that he has been impressive, and that he has a very high football IQ. With Redding, Chapman, Jones, RJF, and Montori Hughes ahead of him, he's going to have an uphill battle making the roster, but maybe he shows enough that they take a chance and give him a roster spot.
Only time will tell.