GREEN BAY - At running back for the Packers, there's both the known and the unknown, and neither is a bad thing.
The known is the Packers have a trio of candidates - Ty Montgomery, Aaron Jones and Jamaal Williams - who have all delivered in the past when handling a feature back's workload.
The unknown is how defenses might react to what Head Coach Mike McCarthy has referred to as a running-back-by-committee approach, at least for the start of 2018, assuming all three are healthy.
More specifically, how will defenses react to Montgomery when he rotates into the game? Montgomery's background as a receiver gives McCarthy the flexibility to line him up in the backfield or in the slot, and then adjust based on how the defense decides to account for him.
If he's in the backfield against an extra linebacker in the box to stop the run, quarterback Aaron Rodgers might signal for Montgomery to go in motion, get him closer to the line of scrimmage, and size up the matchup in the passing game.
Conversely, maybe a defensive back is lined up across from Montgomery in the slot, prompting motion into the backfield to try to run the ball against a lighter box of defenders.
It's a type of game-within-the-game that could ensue, particularly after defenses have already settled in to how they're handling the Packers' other two more traditional backs.
"Mismatches and big plays, that's what I want to bring to this offense," Montgomery said as the Packers wrapped up their offseason program. "When I'm in the game, I want to affect the game. I want to affect the personnel that's out there. I want to affect the defense."
To use his own words, Montgomery is "going to keep the faith" he'll be healthy to do what he wants to this year after two bouts with broken ribs last year, followed by a wrist injury that ended his season.
He's had a busy offseason, impressing McCarthy with his work in the weight room before embarking on the "Tailgate Tour" back in April. Then most recently, he brought his first child into the world, a son he and his wife named Stone.
"Jesus is the cornerstone of the faith, so my hope is he can be a solid rock, a foundation for everyone around him," Montgomery said.
The Packers would like their running game to provide a similar measure of stability on offense. Most of Jones' and Williams' production in 2017 came while Rodgers was out, and the roles constantly shifted due to their own injuries.
The dynamic of a deep rotation, combined with the Montgomery matchup intrigue, will be worth watching. Statistically speaking, all three backs have produced 100-yard games when placed in the No. 1 role, and McCarthy always leaves open the possibility of riding a hot hand in a given game.
"That's what you want," Montgomery said. "You want to know your teammates - even though you're all fighting for a job - you want to know no matter who's in the game, that guy is going to get the job done.
"If Aaron's in the game or Jamaal's in the game or I'm in the game, we all bring something different, and everything that we bring has been effective. You want that. You want depth, you want versatility. I'm excited for what this room brings to the table."
The reps, the roles and the responsibilities are all undefined to a certain extent as 2018 begins. Training camp and the preseason might sort some things out.
Keeping the offense in a rhythm once the regular season begins will be a primary objective, and that's why even with a committee approach, the competition amongst the running backs will be legitimate.
Everyone will work for the opportunity to be the guy, while employing Montgomery in a cat-and-mouse game provides yet another option in the coaching staff's back pocket.
"Ty is definitely a guy that's in the game plan," running backs coach Ben Sirmans said. "I think he's too talented for him not to be on the football field. He can give you some matchup things that we need. He understands what he needs to do.
"All the guys understand what they need to do. I think come training camp, it's going to be an interesting race and battle."