ENGLEWOOD, Colo. — Early in team drills during the Broncos' first training camp practice of 2017, the new offense showed a spark.

Quarterback Paxton Lynch, working with the first team, dropped back to pass and targeted Demaryius Thomas on a post route down the middle of the field. Lynch's spiral was on target and appeared to find a gap between Aqib Talib and Bradley Roby.

Against most defenses, the pass would've ended in a touchdown reception. Not against the "No-Fly Zone".

Roby, positioned behind Thomas, slapped the pass away, and the ball fell to the grass.

Spark, extinguished.

That's the cost of doing business with the Broncos' defense, but there may be no better training for a young quarterback than red-zone work against the NFL's top-ranked pass defense in 2015 and 2016.

"It's kind of tough with those guys," Lynch said. "Obviously we've got a good defense over there, and when you get down there to the red zone, you're going to have to take some chances with the ball and throw it into some tight areas."

Trevor Siemian found similar road bumps during his work in the area of the field where the Broncos struggled in 2016; Denver scored touchdowns on just 46.8 percent of its red zone trips.

After Thursday's practice, though, Siemian complimented Joseph's choice to essentially begin camp where the pace of play is faster and the execution is more difficult. As the Broncos adjusted to the environment, Joseph's choice also served as a way to avoid running his players into the ground early in camp.

"Coach Joseph did something different, which I had never done before," Siemian said. "We got right into red zone today, which I thought was really smart [to] save guys' legs. And guys responded to it really well. That was a little further ahead in the install, which is good too, because you get guys thinking at the same time. I think a really productive day."

And how did Thursday's work in the red zone against a top-notch competition compare to a more routine practice?

"It's fast," Siemian said. "Things happen fast down there, especially with our guys — real tight throws — which is interesting getting back, because usually you're getting back, you're in first install and you're throwing to a bunch of green grass and kind of ease your way into it. But down there it's bang-bang, especially with our guys."

The real contact won't arrive until Sunday, when the Broncos don pads for the first time. And it will be even longer before either Siemian or Lynch are hit. That, ideally, won't come for quite a while, but the first preseason game against the Chicago Bears is sure to see the pair of quarterbacks face a hit or two.

So while Siemian said he and Lynch can still gather "quite a bit" from these unpadded practices, the real answers may need to wait.

"Until you start getting hit, it's a little different," Siemian said. "That's why the preseason games are good. You don't want to get hit too much obviously, but once you get thumping and things like that, it's a little different pace for sure."

Those preseason games may very well decide who's under center on Sept. 11. And when the coaches review film of those contests, the red zone will likely be an area of scrutiny.

The quarterback competition began there Thursday. Is that where it will end?