It hasn't gone according to plan, particularly as it relates to how the Steelers have deployed their defense this season.
In response, the Steelers have been as flexible and as resourceful as they've needed to be.
"Oftentimes when you're faced with adversity during the course of a season, adversity that's created by injury and so forth, people get an opportunity to expand their roles," Coach Mike Tomlin observed in advance of Sunday's AFC showdown against the Kansas City Chiefs.
The latest example of such role expansion occurred in Atlanta, where five players who didn't start the regular season opener on Sept. 7 against Cleveland started against the Falcons (six if you include the first sub-package cornerback off the bench as a 12th defensive starter).
The differences were evident at defensive end (Stephon Tuitt for Cam Thomas), inside linebacker (Sean Spence for Ryan Shazier), outside linebacker (Arthur Moats for Jarvis Jones), both starting cornerback positions (William Gay for Cortez Allen, and Brice McCain for Ike Taylor) and at nickel back (Antwon Blake for Gay).
And the opening day-Week 15 comparison doesn't include players such as defensive end Brett Keisel and outside linebacker James Harrison, who started games and played significant defensive snaps after opening day but weren't available last Sunday. It also doesn't include inside linebacker Vince Williams, who has shared Shazier's position with Spence.
Keisel's on the injured reserve list and done for the season. But players such as Harrison, Taylor, and Shazier could be poised to resume playing more expanded roles, or at least be perceived as available to do so, this Sunday against the Chiefs.
"As you get your health back from the guys who are injured, then you have quality depth," Tomlin emphasized. "It's playing out at the (inside) linebacker position (with Spence and Williams). It's also playing out in the secondary with guys like Brice McCain and Antwon Blake. It's also playing out at the outside linebacker position with guys like Arthur Moats.
"Hopefully, as guys like Taylor, Harrison and Shazier gain their health, we're fortified from a depth standpoint and a quality depth standpoint with playing experience because of it."
Veterans such as Taylor and Harrison have less to establish in terms of their readiness. Shazier is a former No. 1 pick and a player who started five of the first eight games this season. But he's also a rookie who hasn't dressed for seven of the Steelers' last 11 games.
Shazier played one defensive snap on Dec. 7 in Cincinnati and four last Sunday in Atlanta. Tomlin left little to the imagination when asked what Shazier needed to establish a grasp of in practices to warrant more playing time in the games.
"Detail, detail, detail," Tomlin stressed. "It's more about that for a young guy than the physicality of it, anyway. Are their eyes in the right place? Are they utilizing proper technique to play from a penalty-free standpoint? Are they winning the possession downs against skilled individuals?
"So much of that is above the neck and so much of that readiness is reinforced and displayed in a practice setting or a preparation setting. There's a lot to learn from that standpoint as we prepare all of these guys."