Readers have asked The Bee’s Chris Biderman about 49ers receiver Dante Pettis, left, and quarterback Nick Mullens in this week’s mailbag. AP

The 49ers will look for their first winning streak of the season Monday night against the New York Giants behind Nick Mullens, who will be making a second start at quarterback following his impressive debut against the Raiders.

Here’s this week’s mailbag.

Vinnie Levine asks: Dante Pettis, why can’t a guy they traded up for in the 2nd round get on the field?

Click to resize

Pettis is the primary backup to Marquise Goodwin, who’s arguably the team’s most important receiver. And it didn’t help Pettis’ development that he suffered a knee injury against the Los Angeles Chargers in Week 4 that cost him the following three games.

Goodwin played more than 92 percent of the snaps the three weeks before the Raiders game, when he was allowed to rest in the second half because of the big lead. Goodwin’s speed has proven to be an awfully important weapon for coach Kyle Shanahan’s offense — and it’s been needed to help set up everything else, namely the running game. That’s made it difficult for Pettis to get extended action.

I think it’s too early to ring the alarm bells on rookie from Washington. Pettis looked the part during training camp, the preseason and Week 1, when he scored his first career touchdown with an impressive catch in the back of the end zone at Minnesota. His knee injury set back his development and his ability to build chemistry with the team’s quarterbacks (Pettis looked like he had a strong rapport with Jimmy Garoppolo).

I’d expect Pettis’ role within the offense to change drastically next season. The 49ers in the spring could move on from Pierre Garçon and the roughly $23.5 million in base salaries remaining over the final three years of his contract. That could create a void at “Z” receiver which Pettis could step into.

If Pettis doesn’t take significant strides in Year 2 with Garoppolo back, then it’s fair to start wondering if the 49ers made a mistake with the pick. For now, it’s simply too early for me to make a definitive judgment halfway into his rookie campaign.

Fernando D. Rodriguez asks: If Mullens win four or five games, what should be the plan with him? Keep him through 2019 season, trade him?

The 49ers have started three quarterbacks in each of the last three seasons, which points to the value of having depth under center.

I’d imagine Mullens playing well would lead to a competition with C.J. Beathard for the backup job behind Garoppolo in 2019. I’m also not expecting things to be as easy for Mullens going forward, as they were against the uninspired Raiders defense.

I don’t think Mullens will do enough to garner serious trade interest in a way that would make him worth shipping out. Third-string quarterbacks don’t get traded very often and would only net late-round picks if they did. Mullens has more value to San Francisco in his current role than getting back a sixth- or seventh-round draft choice.

And because Garoppolo likely won’t be fully cleared from his left knee injury until training camp, the 49ers will likely keep Mullens around to ensure the club has two capable quarterbacks that know the system.

That’s all speculation, of course. Perhaps the 49ers fall in love with a mid- or late-round quarterback in the coming draft they think they can develop quickly, perhaps allowing them to trade Beathard or Mullens.

But that seems unlikely, given the team’s need for depth at other roster positions. Additionally, you never know what a team desperate for quarterback stability will be willing to offer in a trade (looking at you, Buffalo Bills).

With Garoppolo, Beathard and Mullens, quarterback depth shouldn’t be a problem for the 49ers in 2019. Shanahan and general manager John Lynch team shouldn’t feel urged to trade any away given Garoppolo’s injury status.

Lorenzo M asks: Is Solomon Thomas being used incorrectly? Is this the wrong scheme for him? Is he out of shape? I know it took DeForest Buckner a few years to flash, but when he’s actually on the field he’s never double teamed. Why hasn’t he made any plays yet?

I’ve long argued that Thomas would be best utilized as an interior pass rusher. But he hasn’t played well enough to displace Arik Armstead or Sheldon Day in that rotation. He’s been decent against the run as a defensive end in base downs, but that wasn’t why he was drafted third overall.

I don’t think he’s out of shape. He looks considerably stronger than he did during his rookie year. I think it comes down to confidence.

Apologies for the cliché, but success breeds confidence. Thomas hasn’t been successful yet, particularly pitted against the expectations of a high draft pick. I don’t think getting selected so early in the draft did him any favors. He still has potential to become a game-changing player, but it hasn’t clicked for him yet.

Thomas’ situation is difficult to unpack. The unspeakable tragedy of losing his younger sister to suicide last winter is still something he’s still learning to cope with.

The 49ers have struggled to find a balance of giving Thomas the reps he needs to develop while also giving players the snaps they deserve. Day has been too productive to keep off the field, which has cut into Thomas’ playing time on the inside. How Thomas is used over the second half of the season will be an important development to track.

There’s a reasonable chance the 49ers decline to option to pay Armstead $9 million on his fifth-year option for 2019. That could allow Thomas more playing time in the rotation on the interior in Year 3. For now, it looks like the 49ers got a rotational player, not a star, with the third overall pick.

It’s Uncle Geoff asks: if Demarcus Lawrence hits (free agency) do the 49ers throw all the money at him?

One of the lessons the 49ers learned last offseason was the difficulty in finding pass rushers in free agency. Lawrence and Ezekiel Ansah, arguably the two best free-agent edge defenders, were slapped with the franchise tag by the Dallas Cowboys and Detroit Lions, respectively, and never reached the open market.

There’s a reasonable chance that happens again with Lawrence. Dallas is expected to have some $54 million in cap room for 2019, according to Overthecap.com, which should be plenty to tag Lawrence again at an increased price or ink him to a long-term contract.

But it’s tough to forecast what’s going to happen with “America’s Team.” Changes in the coaching staff could be coming, which could mean a roster reset that allows Lawrence to spring available. He would likely be one of the most in-demand players and the 49ers would likely be aggressive in making a pitch, as they were trying to acquire Khalil Mack before the season and another former Raider, Bruce Irvin, this week, according to a NBC Sports Bay Area report. Irvin reached an agreement with the Atlanta Falcons on Wednesday.

But Lawrence won’t be the only pass rusher available. Kansas City’s Dee Ford (eight sacks in nine games), Seattle’s Frank Clark (7 1/2 sacks in eight games) and New England’s Trey Flowers (three sacks in eight games) are among a the talented group of defensive ends without contracts in 2019 who might not get the franchise tag.

Either way, I’m expecting the 49ers to prioritize pass rushers in both the NFL draft and free agency after making minimal investments in the position over the last two offseasons.

Chris Biderman: @ChrisBiderman