Per ESPN Boston:
Mayo sees reduced role in return
"It was surprising, however, that when the Patriots' defense took to the Heinz Field sod, the defensive co-captain was a bystander, watching the game's first drive from the sidelines.
Despite having Mayo active for the first time since Week 4, the team opted to sit him for the Steelers' first offensive series. The opening drive included three third-down conversions, ending on a Mewelde Moore touchdown grab that gave the Steelers a lead they wouldn't surrender.
In Mayo's place, fellow linebacker Brandon Spikes wore the team's defensive radio helmet for the game, and took over Mayo's usual duties of running the defensive huddle.
"For the plays I was out there, it seemed like [the communication] was okay. Spikes did a good job," Mayo said. "Obviously everybody wasn't on the same page on some plays."
Asked if Mayo would "wrestle" the defensive headset back from Spikes going forward, Mayo left the decision to the coaching staff.
"I'm not sure," Mayo said. "I always say whatever the coaches want to do with the green dot, or with positions, I'm willing to do. I'm not really one to go against the grain."
After missing the first drive, Mayo entered the game on the second defensive series. Despite the defense staying on the field for nearly two-thirds of the contest, Mayo saw noticeably reduced playing time from what he usually receives.
"I felt alright," summarized Mayo. "I went out there and ran around with the guys, so my mentality, my mental state of mind was at a peak today, just being out there with the guys."
Im sure that Belichek is just easing Mayo back in like he did Spikes earlier in the year, but the bigger question is who wears the helmet when Spikes and Mayo are 100%?