This article isn't particularly Colts-related, but it is a fascinating look at how cornerbacks are used in different coverages. Sam Monson from Pro Football Focus zeroes in on Richard Sherman and Nnamdi Asomugha in this piece.
Zone coverage might in theory seem like a much easier defense to play than man coverage, because you’re watching the quarterback most of the time, but these plays show that there is more to it than that. Corners need to be able to understand route combinations, alignment, tendencies and have to learn when zones change from how they’re drawn up on the chalkboard.
It may be physically less challenging at times, but zone schemes can be far more mentally demanding than simply sticking to your receiver like glue and preventing the catch. Some players have that ability to think quickly on their feet and adjust or modify their assignment on the fly, others just don’t.