"The most basic thing about quarterback is just decision making," Flacco said. "When you get a defense that's going to take [the] No. 1 [option] away a lot and then [the] No. 2, it forces you to know your progressions and be a good decision maker. So there's a lot of benefits with that. There's also a ton of benefits of having really tough practices and then going into the games and hopefully making it a little bit easier."

Fangio acknowledged Flacco is "getting more comfortable," but he wants to see more from his starter ahead of the Sept. 9 season opener in Oakland.

"You know, it's a new team, new system," Fangio said. "We all know he can throw well. I think he's just got to get a little bit more efficient. Efficiency means a lot of things: throwing it to the right guy a little bit quicker, throwing it a little bit more accurate, getting more work with these routes and these receivers. We're not there, but we're getting better."

Flacco has played in Broncos Stadium at Mile High before, but he admitted it was "weird" to get ready in the home locker room.

Rookie Drew Lock, who is competing to be Flacco's backup, noticed a "little pep in [Flacco's] step" as the veteran came out to practice.

"I think he's excited to make some more memories on this field in the blue and orange instead of black and purple," Lock said. "I think he's going to do a great job. Like I said before I came in here, I was really excited to learn from Joe and figure it all out."

Lock, it appeared Saturday, is indeed starting to figure it out.

He pieced together several impressive throws during seven-on-seven periods on Saturday, and Fangio has seen the second-round pick's improvement.

"He's doing well," Fangio said. "He had some good periods here today. I think he did his best work in the seven-on-seven, which isn't football. But it's progress. You need to see that progress in 11-on-11 and then ultimately in games. But he's getting better."

Lock said he's felt his progression over the course of training camp, but he recognized he has a lot to improve upon. On Saturday, though, he said he "felt really good."

"I felt all right all day today," Lock said. "It's obviously a little different coming out here with all these people, but we've played in front of 100,000 people [at Missouri] before, so it was just going out there and making plays and just doing what you've done in training camp and just bringing it out to this field instead."

And during his first trip to Broncos Stadium at Mile High, Lock got a sense of how the fans feel about Denver's quarterbacks.