Demarcus Dobbs holds the fate of two positions. As everyone knows by now, the second-year defensive end has been playing tight end this offseason, and he even changed his number - 40 - to the tight end range.
If coaches feel comfortable with him as the No. 3 tight end behind Vernon Davis and Delanie Walker, that could cost Konrad Reuland a spot on the 53-man roster. Reuland is eligible for the practice squad.
What was interesting in the most recent game in Houston was that Dobbs entered as a defensive end when the first-team defense went to its nickel formation. That's the position outside linebacker Aldon Smith - who missed the Texans game - played last season. Dobbs looked good there, and why wouldn't he? He's one of the team's more talented pass rushers. (Smith (hip) is unlikely to play against the Broncos).
That gives the 49ers more wiggle room at outside linebacker. Last year, the 49ers went through the season with four players at the position and noted afterward that it was a risky move.
They bulked up the position by drafting Darius Fleming and Cam Johnson. Both, however, have been injured through most of the offseason and neither figure to be on the 53-man roster on Sept. 9. Dobbs could serve as an emergency fourth outside linebacker or at least someone who could provide relief on passing downs.
"Heck yeah," Jim Harbaugh said when asked if Dobbs could be worked into the regular-season rotation as a third-down pass rusher. "He's coming along real nice. I'd anticipate using him in the regular season in that regard."
The odd man out in that scenario would be Eric Bakhtiari. He's done everything that's been asked of him this offseason, and he leads the 49ers in both tackles and sacks through two games. Bakhtiari also is good on special teams, which should help his chances.
Still, the 49ers have to think about the 48 players who will be active on game days. The argument could be made that Dobbs - who plays offense, defense and special teams - would be a more useful player to have on the active, 48-man roster than Bakhtiari. Unlike Reuland, Bakhtiari has no practice-squad eligibility remaining.
Safety: Vic Fangio lamented last week that none of the understudy safeties have stepped forward and that he'd like to see one or two separate themselves over the next two games. C.J. Spillman was arguably the 49ers' best coverage player on special teams last year, and he's likely to earn a spot.
After that, it's a four-way race among Darcel McBath, Trenton Robinson, Michael Thomas and Colin Jones. McBath has an advantage in experience, Robinson and Jones were sixth-round picks - that always helps a player's chances -- while Thomas has the ability to play both safety and nickel cornerback. Jones started to come on as a special teams player in the second half of 2011 and could make the team based on that alone.
Quarterback: The 49ers coaches probably have a favorite by now in the competition for the No. 3 spot. But they're not telling anyone, perhaps in an effort to see if there's interest in a trade. Who enters the game after Colin Kaepernick will be interesting. Will the No. 3 player be the one the 49ers like the most? Or will it be the one they want to trade the most?
Running back: With Brandon Jacobs (knee) out for the game, Anthony Dixon likely will get a lot of carries in short-yardage situations. Greg Roman publicly pumped Dixon up on Wednesday. But it might have been to help the running back find a future employer. I'd think the Colts - who were clobbered by Dixon in 2010 - might be interested.
-- Matt Barrows