49ers Notebook: Kaelon Black, Stribling stand out vs. Chargers; Left guard competition could go on for a while

49ers fans who tuned into Thursday's preseason game against the Los Angeles Chargers came away with plenty to cheer about as their team handed the Chargers a 41-17 beatdown following what was, by multiple accounts, a shaky week of practice.

The 49ers had some problems on defense in particular against the Chargers when the two teams held joint practices earlier in the week, but the vibe was much better after the team held the Chargers in check on Thursday. There were plenty of positives to take from the game, including the performance of rookies De'Zhaun Stribling and Kaelon Black. Those players and much more were among the topics of conversation following the game, which we'll run through in this version of 49ers Notebook.

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Despite drop, Stribling further proves he'll have a big role

The bad news -- rookie wide receiver and second-round pick De'Zhaun Stribling dropped what would have been a likely touchdown against the Chargers on Thursday. The good news -- Stribling's stock stayed the same despite the drop, as he once again showed he'll most likely play a significant part in the 49ers' offense this season.

Coming off a seven-catch debut in a loss to the Tennessee Titans last week, Stribling produced early and often against the Chargers, catching four passes for 46 yards. He once again looked like the next version of Jauan Jennings by making plays on third down while also connecting early with Brock Purdy.

Stribling's drop came with backup Mac Jones in the game. Jones launched a pass deep downfield that was on target for Stribling near the end zone, but Stribling couldn't haul it in. 49ers head coach Kyle Shanahan told reporters afterward that the catch would have been a difficult one but that Stribling should have caught it nonetheless.

"That's his strength is his hands," Shanahan said. "It was one that Mac let go really early. When you call a double move down there, you get that ball up and down. Mac threw it about as early as you can, so I don't think he picked it up until it was about three yards away from him, which makes it a real tough catch. But he's got the ability to do it, so he needs to come down with that one."

Either way, Stribling continued to show on Thursday that the 49ers are looking smarter than their critics who called them out for drafting him higher than expected. It's obviously impossible to say for sure at this point how Stribling will perform through four quarters against a first-team NFL defense, but after his first two games, it's hard to imagine he won't see a good amount of success as a rookie.

Kaelon Black's promising debut

Thursday night marked the first game action for rookie running back Kaelon Black, who, in limited carries, showed why he may be called upon quite a bit this season.

Black, who missed time over the past month with an adductor injury, ran for 33 yards on eight carries in his first NFL game action. Black ran through some tackles while also showing some spark.

Thursday night marked Black's first game action since helping the Indiana Hoosiers win the national championship against the Miami Hurricanes in January. He was all smiles when talking about the chance to play in an NFL game.

"It felt great," Black said Thursday. "It's been a while since we played back in January for the national championship. Getting out here and playing NFL football, it's just a blessing to be out there and doing it."

As was the case with Stribling, the selection of Black drew a healthy amount of criticism, given the fact that the 49ers picked him in Round 3 while some analysts projected him as a late-rounder. But so far, he looks the part.

"I was real happy with him," Shanahan said. "Seeing him for his first practice there on Tuesday versus the Chargers, you could see it a little bit. I thought nothing changed today. He ran real physical. We'd love to keep him in there a little bit longer, but being his second day back, we were smart with him. I'm pretty sure he got out healthy, and that'll give him a chance to have four good days this week."

Left guard competition may (or may not) last a while

Who will win the ongoing battle to become this year's starting left guard for the 49ers? The answer may not come until sometime after Week 1.

Among the competitors are rookie and fourth-round pick Carver Willis, veterans Robert Jones and Austin Pleasants, and second-year lineman Connor Colby. Each of them got time at the left guard spot on Thursday night except for Jones, who is out with an undisclosed injury.

"It's going to go down to the wire," Shanahan told reporters Thursday. "It seemed like those guys did good today."

A reporter asked Shanahan if he thought the competition could extend past Week 1.

"Possibly," Shanahan said. "We've got to pick one for week one, and hopefully one of those guys will separate themselves and make that a little easier for us. But Week 1's just Week 1. It never stops. It's always going."

Injuries have made things more difficult at the position, as Willis has missed time due to a concussion and now Jones and possibly Pleasants may be out. Pleasants, who saw time at guard Thursday night after starting at tackle, left the win against the Chargers with a knee injury. Perhaps the door will be opened for Willis now that he's back on the field, and for Colby, who has been able to stay healthy.

"The guys that are battling, they haven't all had a consistent three weeks or month to do it, especially Carver just coming back missing those first two weeks," Shanahan said. "And now Robert Jones is out. Connor Colby, he's been getting a lot of reps there too. All those guys are in the battle."

Quarterback reflections

Three quarterbacks played for the 49ers on Thursday night -- Brock Purdy (4/6, 29 yards), Mac Jones (6/13, 89 yards), and Adrian Martinez (8/17, 57 yards). Purdy's snaps were limited, as one might expect, and he left the game after one 12-play drive. Jones had some ups and downs, connecting on some big passes while missing others. Then Martinez had the most eventful night, throwing two interceptions but also a touchdown pass and running for a touchdown while leading the 49ers on three second-half scoring drives.

Shanahan gave some quick thoughts on each quarterback while speaking to reporters on Thursday.

"(Purdy) moved the ball decent," Shanahan said. "We would have liked to go down and score... He converted three third downs, which was big. I thought he'd get two drives, but I think it was 12 plays, so we took him out after that. Then Mac came in; we really didn't want him to go into the third. He missed a couple of throws but also had a touchdown that I thought was a pretty good throw that Strib just ended up dropping. Then Adrian came in -- I know he had those two picks. The second one I thought was unfortunate. He was trying to make a play down the sidelines. But I also thought he did some good things too."