ENGLEWOOD—Roster building 101 is never about the rookies.

They may draw all the buzz. But consistent, organizational success begins with a quantum leap from last year’s rookies.

Trevor Siemian didn’t play as a rookie but became a Pro Bowl alternate in year two. Demaryius Thomas struggled as a rookie before he began to break out in year two. Von Miller may have been the NFL’s Defensive Rookie of the Year in 2011, when he had 11.5 sacks, but to this day, his career-best statistical season remains year two, when he 18.5 sacks.

Look at the NFL’s best player of the past 16 years – and arguably of all time. New England’s Tom Brady completed one pass as a rookie in 2000. He was a Super Bowl MVP in year two.

So while Garett Bolles, DeMarcus Walker and Carlos Henderson have been the subjects of countless stories sprouting from UCHealth Training Center the past six weeks, the key to the 2017 Broncos may be to get much better production out of 2016 first-round pick, Paxton Lynch, second-round selection Adam Gotsis, and the likes of Justin Simmons, Devontae Booker, Connor McGovern, Andy Janovich, Will Parks and Riley Dixon.

“I forget which vet told me, but I’ll never forget it,’’ Simmons said Thursday. “When we were midway through the season … one of the vets told me: In college, you really just play football. But in the league, you learn football.’’

Hmm. A unique way to put it. Please explain.

“Here, I’m actually learning offenses,’’ said Simmons, who was a third-round pick out of Boston College in the spring of 2016. “I’m learning tendencies. I’m learning offensive coordinators likes and dislikes when they’re at a certain yard line on the field; if they’re at the plus or the minus. If it’s second-and-10 or second-and-seven.

“It’s things like that that they (veteran players) all know which makes them so successful on the field instead of just going out there and playing the coverage that’s called. That’s why they’re so successful because of their study of the game. For myself, that’s the level of competitiveness that I want to be at.’’

The progress of last year’s first-round pick, Lynch, has been well-documented. He is in a quarterback competition with Siemian that remains too close to call as the Broncos’ wrapped up organized team activities (OTAs) Thursday. The Broncos will conclude their offseason program next week with a three-day, mandatory minicamp.

Lynch either steps up in year two – or sits back and waits until year three.

The progress of last year’s second-round pick, however, has barely been observed.

“Physically, he is definitely a new player,’’ Broncos head coach Vance Joseph said of Gotsis nine days ago. “He’s 300 pounds, probably 13 percent body fat, which is amazing. He is explosive and athletic. Now he has to get reps and play more. He’s a second-round pick for a reason. That’s what I saw on tape in college, this guy who we’re seeing now. I’m excited about him. He’s finally healthy and you can tell.”

Simmons and Parks, as backup safeties to vets T.J. Ward and Darian Stewart, will get pushed in training camp by “premium” undrafted rookies Jamal Carter and Orion Stewart.

Booker’s is staring at an unofficial depth chart of veteran Jamaal Charles ahead of him and rookie De’Angelo Henderson behind him.

McGovern didn’t get a game-day uniform last year but has been the No. 1 center this offseason while Matt Paradis heals from his hip surgeries.

For the Broncos to rebound and make the playoffs in 2017, they will need one or two – maybe even three or four – of their 2016 rookies to come on.