ENGLEWOOD, Colorado — Peyton Manning's summer was both dazzling and perplexing.
Practices consisted of sprint-outs, roll-outs and bootlegs from under center, play-action passes from the pistol formation and scrambles for first downs in defiance of his 39-year-old legs.
Preseason games were filled with empty backfields and shotgun formations that produced a paucity of points and plenty of angst among Broncos fans and fantasy football owners alike.
Which Manning shows up Sunday is the subject of much debate.
"The last three years he's been here, there were (preseason) games we didn't score points and we'd come out and score 35, 42 points" in the opener, wide receiver Demaryius Thomas said. "So, I don't know if it's by design or not, but it happens."
If Manning is concerned that he didn't find the end zone in August, he didn't show it Wednesday.
"Hey, I'm looking forward to Sunday and looking forward to seeing how we're going to perform," Manning said. "We've got some new guys playing and we've got some new things that we're doing and I'm excited to see how we're going to do. I've said all along the key for us is to improve throughout the season, throughout the course of a game.
"Baltimore's an excellent defense. Are you going to dominate all four quarters? I don't think anybody's ever done that against Baltimore, but hopefully you can win enough plays and be efficient enough to win the football game."
Ravens coach John Harbaugh said one of the biggest challenges he's facing this week as he prepares for the opener was figuring out how Broncos coach Gary Kubiak, his former offensive coordinator, was adapting his scheme to fit Manning's skills.
"The teams that play him in Week 3 and 4 and 5 and 6 and down the road will have a better feel for that than we will," Harbaugh said. "I'm sure that they didn't show in the preseason everything that they're planning on doing."
The Broncos showed almost nothing in the preseason, in part because Manning never had Pro Bowl receivers Thomas and Emmanuel Sanders together with him on the field.
They also decided to use training camp to get a feel for the future. General manager John Elway said he liked what he saw in Brock Osweiler, who's entering his fourth season as Manning's backup. He also liked rookie Trevor Siemian, so much so that he had to keep the former Northwestern QB on the 53-man roster rather than risk trying to slip him through to the practice squad.
Manning made cameos in the second and third exhibition games and didn't find the end zone in nine full possessions. He said he would like to have played more — and better — but was satisfied with his preparation for his 18th NFL season.
Harbaugh may not know exactly what to expect Sunday, but he should have a pretty good idea. Under the tutelage of Kubiak and his top lieutenant, Rick Dennison, last year, Ravens quarterback Joe Flacco had the best season of his seven-year career.
"I'm sure that Peyton is having a great experience with them," Flacco said. "... They just helped me play fast, play with a quiet mind, be confident and make quick decisions. I think that our line played really well last year under their protection scheme and I think that helped out a ton."
That will be important for Manning, who has four new O-linemen, including two novices in left tackle Ty Sambrailo and center Matt Paradis.
Ravens running back Justin Forsett went from journeyman to Pro Bowler in Kubiak's zone blocking scheme last year, and Harbaugh said Denver Pro Bowler C.J. Anderson should be in for a similarly spectacular season.
"He's a downhill, one-cut, very physical guy," Harbaugh said. "Different kinds of backs are good in this scheme, but they've got two of them. Ronnie Hillman does it differently than C.J. does it. I think they've got two guys with different styles that run the scheme very well."
Notes: Players voted Manning, DE DeMarcus Ware and S David Bruton Jr. as team captains. ... DE Kenny Anunike (knee) was the only player to sit out practice.
Follow AP Pro Football Writer Arnie Melendrez Stapleton on Twitter: http://twitter.com/arniestapleton