Three things revisited: Broncos-49ers

Looking back on three things discussed here before the San Francisco 49ers' 2013 exhibition opener, a 10-6 defeat to the Denver Broncos at Candlestick Park:

1. Young receivers. The 49ers would like 2012 first-round pick A.J. Jenkins to seize the starting job opposite Anquan Boldin. But Jenkins did not make a strong positive statement in this game. "Uh, could have been better," said coach Jim Harbaugh afterward. Overall, the 49ers targeted Jenkins three times and got two turnovers on those plays: Jenkins lost a fumble following his lone reception, and Colt McCoy overthrew him on a deep route, resulting in an interception. Marlon Moore adjusted to the ball nicely and made a low grab on an across-the-body throw from starting quarterback Colin Kaepernick. The Broncos tackled Moore short of the first down, but this was still an impressive reception. Ricardo Lockette drew a penalty on the perimeter. He also contributed with a special-teams tackle deep in Denver territory. Rookie second-round choice Vance McDonald is a tight end, but he factored in the receiving game and certainly looked the part while catching four passes for 66 yards.

2. Secondary dynamics. Tramaine Brock, in the lead for the No. 3 corner role over Nnamdi Asomugha while the team prepares to welcome newly-signed Eric Wright, had tight coverage on an incomplete sideline pass from Peyton Manning to Demaryius Thomas. Asomugha made a sure tackle in zone coverage to stop the Broncos on third down. At safety, C.J. Spillman made a tackle for loss. First-round pick Eric Reid delivered a couple of forceful hits. It will be helpful to get an update from defensive coordinator Vic Fangio as the 49ers look to identify their third corner and starting free safety for Week 1.

3. Backup QBs. Grading backup quarterbacks behind backup offensive lines can be tricky. McCoy looked good infinding McDonald in stride for a 19-yard gain early, but he attempted only seven passes overall and was picked off once. McCoy apparently suffered a shoulder stinger, Harbaugh told reporters after the game. Scott Tolzien completed 15 of 26 passes for 158 yards and a pick. His quick strike to Austin Collie on a late fourth-down play sustained a drive. To be continued.