Short night for starters in preseason opener

On a don't-blink-or-you'll-miss-them kind of night, the Denver Broncos rode an opportunistic defense to a 10-6 victory over the San Francisco 49ers at Candlestick Park in the preseason opener.

Here is what we learned about the Broncos:

  • With some injury issues in the offensive line, the Broncos practiced some risk management as quarterback Peyton Manning played just seven snaps, finishing his night 2-for-4 passing for 13 yards. With left tackle Ryan Clady still out as he continues to work his way back from offseason shoulder surgery, the Broncos got a vivid snapshot as to why they didn't want to leave Manning in too long. On the last of Manning's four drop-backs the 49ers' Aldon Smith overwhelmed Clady's replacement, Chris Clark, to jostle Manning.

  • Manny Ramirez started his first NFL game at center Thursday night and Orlando Franklin, who missed most of Monday's practice and all of Tuesday's with a hip injury, made the start at right tackle. Had the Broncos been a little more settled along the offensive front, Franklin might not have started a preseason game just two days after being held out of practice. It is clear, after seven snaps, that when the Broncos are in a three-wide receiver look, the offensive line is still a work in progress.

  • Those protection issues -- second-team quarterback Brock Osweiler was routinely chased from the pocket behind a line of backups -- will impact how much the Broncos can work out of their preferred three-wide look. If they can't hold up with just five blockers up front, the Broncos will have to work out of two-tight end and two-back looks offensively. The Broncos did work considerably more out of those bulkier formations when Osweiler was in the game.

  • The fact the Broncos' first touchdown of the preseason came on defense was a nice start -- especially for a team that dropped its share of interceptions and saw many forced fumbles recovered by the offense. Linebacker Nate Irving knocked the ball free from 49ers rookie running back D.J. Harper and Shaun Phillips scooped up the loose ball and ran nine yards for the score. That's exactly the kind of play defensive coordinator Jack Del Rio has preached to this unit. They simply didn't find themselves with enough of the fumbles they caused -- finishing third in forced fumbles but tied for just 19th in recoveries. "Those kinds of things are momentum changers. We want those," Del Rio has said. The Broncos forced three turnovers in the first half and had a fourth to start the third quarter.

  • The Broncos wanted to see how Duke Ihenacho would handle starting at strong safety, and they got their answer. Ihenacho has made a long climb from being an undrafted rookie who spent most of 2012 on the team's practice squad to the starting lineup to start this training camp. He had seven tackles in the first half -- three tackles on the Broncos' first defensive series -- forced a fumble and nearly had an interception. It means a veteran like Mike Adams is going to have to find a way to carve out a role on special teams, because Ihenacho showed he's ready for the job.

  • Defensive linemen Malik Jackson, a fifth-round pick by the Broncos in the 2012 draft, showed his versatility by taking snaps at both defensive end and defensive tackle. Despite the fact that the Broncos used their first-round pick on Sylvester Williams and signed Phillips during the draft weekend, Jackson should still carve out a situational role in the defense because he creates pressure from both an edge spot as well as on the interior.

  • Stewart Bradley, a 29-year-old who signed a one-year deal in free agency, got the start at middle linebacker. This definitively showed he has created far more competition for the job than some had thought. Irving had been the starter throughout offseason workouts and into the early days of camp, but Bradley has played good assignment football and played his run fits with discipline. Bradley started to appear with the starters earlier this week and opened in the middle Thursday night. Irving was active in a backup role, however, so don't chisel Bradley's name on the depth chart just yet.

  • Ryan Lilja might have come out of retirement just a week ago, after having knee and toe surgeries earlier in the offseason, but the Broncos gave him plenty of work Thursday night as the No. 2 center. While Lilja worked with the starters this past week at both left and right guard, the Broncos are hopeful he can quickly move into the No. 2 role at center and push Ramirez for the starting job. Ramirez is bigger and more powerful, but Lilja has more experience with Manning -- having played 2004-2009 in Indianapolis -- and moves better. With the number of zone-run plays the Broncos showed against the 49ers, movement will be a must. Ramirez had a holding penalty on a zone run early in the game when he didn't beat the defensive lineman to the spot.

  • With Joel Dreessen expected to miss the remainder of the preseason after arthroscopic knee surgery, his second on his left knee since late May, and Jacob Tamme still working past a thigh injury, Julius Thomas will have a chance to be the go-to tight end in the passing game. He showed his athleticism with four catches against the 49ers. His size (6-foot-5, 250 pounds), speed and reach will make him a tough matchup if he can keep the momentum he's had in camp thus far. Thomas ran away from linebackers Thursday night and towered over the safeties who tried to check him.

  • Of the Broncos' undrafted rookies, running back C.J. Anderson made the most of his opportunities, finishing with a team-leading 69 yards on his 15 carries. Anderson has flashed plenty so far in this training camp but has occasionally made assignment errors that will impact his ability to make the roster. If he cleans up the mistakes and avoids concentration lapses, he showed he has something to offer in the run game.

  • The Broncos have spent some time in the offseason adding the pistol formation into the offense, which they ran sporadically Thursday with mixed results. They'll have to control the middle of the formation better than they did against the 49ers to make it work.

The Broncos, after a late return to Denver scheduled for the wee hours of Friday morning, will give the players Friday off. Those who need treatment for injuries will make an appearance at the team's Dove Valley complex, but they won't all hit the field again until Saturday morning's practice.