The team announced a contract extension with safety Aaron Williams on Wednesday.
A person who has seen the deal tells NFL Media Insider Ian Rapoport it is a four-year contract worth $26 million, with another $1.25 million in incentives.
Struggling to find a position in his first two seasons, Williams found a home at strong safety opposite Byrd and Da'Norris Searcy last season. He has the ability to handle cornerback in subpackages, increasing his value to the Bills.
"Aaron Williams is a versatile player who has grown into a key playmaker for our defense in recent years," general manager Doug Whaley said in a statement. "He had an extremely productive season for our defense in 2013. Aaron is the type of young, core player we targeted early in the process to retain for years to come and this will be our philosophy moving forward."
We fully expect Williams to step into Byrd's role as the "center fielder" in Jim Schwartz's secondary. Still, a team source told Rapoport that Williams' signing is "completely independent" to Byrd's future with the Bills.
Without Byrd and defensive coordinator Mike Pettine, this defense can be expected to take a step back in 2014.