As the Lions' centre, Norman is tasked with calling the blocking scheme before the snap of the ball — a decision that often determines the success or failure of a play.
The wrong call could leave an opponent unblocked and result in a season-altering turnover or injury, while the right one might give the quarterback extra time to throw or the running back an opening for a big gain.
"I played centre back in the day and I generally know what the call is and I can be guilty of making it before (Norman) does sometimes," said Valli, the Lions' right guard. "Last year if he made the wrong call and I called him off he would apologize to me. This year he made the wrong call and I tried to change it and he turned around and told me to shut up."
Valli said that development from the usually soft-spoken Norman was encouraging and bodes well for the group moving forward.
"I patted him on the back after. I said 'Good for you. Regardless of whether it was right or wrong, you're taking that role as the field general,'" Valli continued. "'Whether you're right or wrong, you're it saying with confidence.'
"Volume reflects confidence and Matt's really coming into his own."
The Lions will need that leadership and confidence after losing three key pieces to the offensive line this off-season after Angus Reid, Ben Archibald and Patrick Kabongo all retired.
While Archibald and Kabongo both played in 2013, Reid sat out the entire campaign with a back injury, but was on the practice field every day helping to mentor his replacement at centre.
"It was unfortunate that he was injured, but the feedback and the knowledge that I gained from just having him around was unbelievable," said Norman, who is entering his third CFL season. "We miss him here. He was a great person in the locker-room and a great person on the field."
Now the elder statesman on the offensive line, Valli said it's strange not having Reid, Archibald and Kabongo at camp even though he knew the three veterans were winding down their careers.
"It's a transition that eventually happens to everybody," said the 30-year-old Valli. "One day you're a young guy and you look up to a bunch of older guys and it's like that for a long time, and then one day they're all gone. You have to just accept that as the nature of the game."
Lions offensive co-ordinator Khari Jones called rebuilding the offensive line a "big project," but added that having Norman — who turns 26 later this month — take a leadership role is critical to the unit's cohesion.
"The first year that anybody plays it's more listen than talk and trying to figure things out and trying to get the speed of the game," said Jones, who's in his first season with the Lions. "You want a guy who's confident in his abilities and Norman is a guy who we're going to lean on. We don't have a lot of experience, but as the centre you have to be ready to call the shot and I think he is."
Lions quarterback Travis Lulay said he's seen a definite shift in Norman's demeanour since camp at Thompson Rivers University got underway last weekend.
"He's a much more assertive guy this season," said Lulay. "Matt's a real nice guy off the field — really conscientious of other people. I think it's important to him to have the guys hear him, especially with Angus not around.
"It forces him to take that more assertive role and so far, so good."
The Lions had difficulty running the ball for long stretches last season, but got things together before the playoffs and rushed for an average of just over 200 yards in their final three games.
It's a trend they want to continue with Jones calling the shots in an aggressive scheme.
"There's always something to prove," said Norman. "Every offensive line wants to be good at running the ball and I think that's where we're going to establish this year. We have a great mindset and great set of players."
Among those looking to crack the Lions' offensive line is Andre Ramsey, who suffered a season-ending knee injury at last season's camp. A four-year starter at Ball State, the American tackle previously spent time with five NFL teams and looks like a good bet to make the roster on the critical left side.
"I'm learning a lot about the nuances of the CFL game," said Ramsay. "You need to be a lot more patient. I'm used to getting my hands on (defensive linemen) right now, and pretty much if I get my hands on them, it's over. Now they have that extra yard, which allows them to go in or out."
Apart from Norman and Valli, other returnees include guard Kirby Fabien, who also suffered a knee injury in 2013 and missed most of his rookie campaign, and veteran right tackle Jovan Olafioye.
Norman said the group is using training camp to iron out the wrinkles and get to know each other, something that wasn't as necessary in years past with so many familiar faces.
"Offensive line is a position where trust is a huge factor and this is a great time to spend with the guys," he said. "You hit the hot tub and the pool and get out on the practice field and you're always together so you get to form those relationships and establish that trust."
Valli is entering his ninth season with the Lions and has been impressed with the stable of young players that has lessened the blow of the recent retirements.
"That's how a team develops over time — you keep bringing good people in and that's how you fill the void when guys move on," he said. "There comes a time when you have to make that transition and thankfully they've brought in not only some really nice guys, but some guys who can play football."