Under normal circumstances, though, the injury to Bret Lockett in the preseason game against the Tampa Bay Buccaneers wouldn't have been viewed as a huge blow to the depth at safety.
Of course, any average fan knows about the heated rivalry. It can't be too surprising to see the gamesmanship on Bill Belichick's behalf to pick up a guy from the rival to potentially get some inside knowledge out of him.
To pick him up for that reason alone, though, would be superfluous.
Hardcore fans know that Belichick has been trying out his options at safety for the past few days, rotating Brandon Meriweather and Sergio Brown.
The injury to Lockett, combined with the injury that has kept James Sanders out since the beginning of training camp, has forced the Patriots into a three-deep safety situation. But Brandon Meriweather, Patrick Chung and Sergio Brown are the only healthy ones on the roster. They've even played wide receiver Buddy Farnham in some spots at safety to compensate.
That being said, it shouldn't come as a surprise if Ihedigbo doesn't make the team. Sure, he had his best season in 2010 with 22 tackles and three sacks, but Brown contributes on both defense and special teams, and has been in the system for a full year, including two training camps.
If being brought in to address depth concerns at safety, Ihedigbo would have to learn the playbook incredibly quickly. He isn't at quite a disadvantage, as the playbook appears fairly new to what we've all seen over the past 11 years. Nonetheless, the Patriots have been in full swing in camp for over two weeks.
He would also have to bank on long-term injuries to James Sanders and/or Bret Lockett. Who knows when one or either will return. One could speculate that the signing indicates a more serious situation for the two injured safeties.
It's unlikely Ihedigbo is anything more than special teams insurance, but the Patriots are just walking through the junk yard, kicking every tire on the ground. If they think it might fit, they take it out for a spin. The worst case scenario is that when it pops or wobbles uncontrollably, they just bring it back and try out another one.
Either way, it's better to have the insurance of having an extra tire floating around. You just never know when you'll end up with a flat and need a spare.