Eight in the Box: Must-keep free agents

Welcome to “Eight in the Box,” a new NFL Nation feature that will appear each Friday during the offseason. This week’s topic: Which free agent is essential for each team to keep from its 2012 roster?

Arizona Cardinals: Cornerback Greg Toler. The Cardinals’ defense will undergo something of a makeover with new coordinator Todd Bowles calling the shots, but that’s more likely to affect the front seven. A good, big, young cornerback is tailor-made for any defense, and Toler improved during his fourth season in 2012. He shouldn’t break the bank, either.

San Francisco 49ers -- Tight end Delanie Walker. The beauty of the 49ers’ offense rests in its multiplicity, and Walker, the 6-foot, 242-pound tight end who can block, catch, cover kickoffs and run a 4.5 40, is aptly nicknamed the “Swiss Army Knife.” Safety Dashon Goldson is a priority as well, but Walker’s versatility is too valuable to pass up.

Seattle Seahawks: Defensive tackle Alan Branch. The Seahawks’ hybrid defensive front is predicated upon two reliable tackles who can eat up space and provide an interior push. Branch is a mountain at 6-foot-6 and 325 pounds, and he frees up space for teammates.

St. Louis Rams: Defensive end William Hayes. Head coach Jeff Fisher heavily influences the defense in St. Louis, which starts with pressure. That should only increase after recently tabbing Tim Walton as his new defensive coordinator; Walton comes from a pressure-heavy system in Detroit. Hayes, Pro Football Focus’ 15th-best 4-3 defensive end in 2012, is a critical cog in St. Louis’ ability to disrupt opposing passers.

Field Yates is a contributor to ESPN Boston.com and ESPN Insider.

Mike Sando will return to the NFC West blog next week.