Analysis of Patriots strategy can be tricky because Bill Belichick is not only so circumspect but also tends to be a step ahead of league-thinking.
As is often the case in professional sports, though, the answer to our question is money.
Arrington was scheduled to earn $3 million and account for $4.625 million on the salary cap, high figures for a niche player who took the field on just 40.9 percent of defensive snaps last season. Although Arrington stifled T.Y. Hilton in a pair of meetings with the Colts, he was also benched in the second half of the Super Bowl.
The Patriots tend to use September and early October to tinker with different combinations before finding their identity by midseason.
Just as Blount didn't materialize as a backfield savior until November, the same could hold true with the cornerback experiments in 2015.