© Stan Szeto-USA TODAY Sports

SANTA CLARA – It’s getting to be crunch time for John Lynch and Kyle Shanahan. Heading into Saturday’s third preseason game against the Kansas City Chiefs, which represents the only real, extended look at most of the 49ers’ starters in the preseason, the team’s general manager joined Tolbert, Krueger and Brooks on KNBR 680.

Bosa, Verrett looking iffy for Week 1

It was always going to come down to the wire for Nick Bosa and Jason Verrett. Both suffered near-identical (severe) sprained ankles on the 10th day of practice on August 7, putting them on similar timelines which targeted a Week 1 return.

That remains to be the case, but if it felt at one point like Bosa and Verrett were more likely than not to play in Week 1, that is not where they stand now. According to Lynch, those decisions might come at the last possible second.

“Nick Bosa, he’s coming along really well,” Lynch said. “I think, truly, Week 1, that’s, I don’t know, 50-50 as to whether he makes it. It’s going to be touch-and-go, and Verrett the same way. We’ll learn a lot more. Everyone’s doing really good in their rehab, it’s just a lot of those we knew would be close, so we’ll see as things get a lot closer.”

As for Dee Ford, who is expected to return to practice next week, Lynch said he’s “doing really well” and was excited to see him back out running in practice (he was out on the practice fields, not in pads, but throwing the ball around and doing individual workouts on Thursday). Lynch said he won’t play in the preseason, essentially to ensure his chronic knee tendinitis doesn’t bother him (or bothers him as little as possible) in the regular season.

Lynch was less exact on Jerick McKinnon, but suggested that he’ll back practicing soon. He’s a very strong candidate for the injured reserve-return designation (although that has not been stated or implied yet by the team), which would mean the 49ers would have to sacrifice a 53-man roster spot for him on cutdown day, put him on IR-return the following day, and hope to sneak a player onto the practice squad and sign him. He would have to remain on IR for eight weeks and be eligible to play in Week 9.

“McKinnon, that’s something that’s been a very fluid situation,” Lynch said. “We’re just trying to be judicious. Last time, I don’t think we rushed him when he had his flare up, but it didn’t work. So you go back and you say, ‘What can we do better this time to give him the best possible chance?’ We’re trying to do that, but I think that should be soon.”

Questions and expectations on the offensive line

The loss of Shon Coleman was no small thing, no matter how many people like to pretend that backup injuries are insignificant. Coleman was an insurance policy for Joe Staley and Mike McGlinchey, and a fantastic one at that. If Staley and McGlinchey are completely healthy, then it makes little difference, but having a comfortable swing tackle backup provides a valuable sense of ease to a coaching staff and front office.

That ease is gone, and now rookie Justin Skule and veteran Sam Young are next up as the swing tackle backups (it’s unclear if the 49ers would take two tackles, but based on Lynch’s comments, the preference seems to be for the rookie Skule if it comes down to him and Young, which is likely).

“O-Line depth, when you have it, it’s rare,” Lynch said. “We felt like we bolstered it a little bit. Shon Coleman, he’s a guy we traded for going into last year, and he really developed, I think was probably as improved as any player on our roster through this offseason. That really hurt to see him go down because we really felt like we had another starting tackle as our swing guy, so now the pressure goes on a guy like Justin Skule from Vanderbilt, a rookie. But he’s got to step up his game. Sam Young, we went out and got.”

Finally back is the oft-injured Josh Garnett, who’s got a hand cast on as he returns to practice from finger surgery. Najee Toran has received a smattering of snaps in his, Mike Person and Weston Richburg’s absence across the line, and looks like he’s the favored backup guard at this point.

Lynch said Garnett will need to prove himself.

“Good news is [Garnett’s] been back out at practice, albeit in a cast this week,” Lynch said. “Josh is going to have to come show us that he’s ready to compete.”

Meanwhile, he said Richburg’s rehab has “gone extremely well” and the team expects him, as Shanahan has previously stated, to be back practicing with the team before the final preseason game against the Los Angeles Chargers. Person is also back, and Lynch said the team appreciates his toughness (he has a knack for playing through injuries, arguably to a fault).

Defensive line depth and trade talks

The one area the 49ers have a good problem to deal with is the defensive line. They took nine defensive linemen on the 53-man last year, and it’s looking necessary to take 10 this season. Guys on the bubble are Jullian Taylor, Damontre Moore and Kevin Givens (Jeremiah Valoaga’s name could be thrown in there, too, with the way he’s played in the first two preseason games), and the 49ers would feel more than comfortable with any of them on the roster.

It’s going to be a good headache for Lynch and Shanahan… and yes, the phone has been ringing.

“That’s one of the things that we’re happy about, but it’s also going to make for some tougher decisions,” Lynch said. “The back end of our roster, there’s some real strong players, more than we can keep. That’s what you want. It will make for some tough decisions. I’d be lying if I told you people hadn’t been calling, but we’re still trying to figure it out ourselves and what the right mix is. Sometimes, that doesn’t always mean the 53 most talented guys… Those are good problems to have, but there are a ton of discussions that are really tough ones because we have a lot of guys that are capable of making this roster.”

Other notes: Tartt’s ceiling, preseason rest trends, Garoppolo Game 4? and Hard Knocks

• Jaquiski Tartt was one of the best players on the field in the second preseason game. He marauded around the field and wreaked havoc both in and outside of the box with five tackles and two PBUs. Lynch said he gave Tartt advice before the last preseason game, but didn’t want to take credit for his performance:

“If he can play like that every week, Larry, he’ll do very well in this league for a long, long time,” Lynch said. “I was able to share some things. I shared that story about my own personal experience going through the stingers, that’s what Quaski went through last year. He had a very good camp, but he has been a little hesitant in training camp to actually go through and hit someone. And I was able to share some of those thoughts with him and man, did he go out and respond. I’m not taking credit for that, Quaski gets that credit, but man was that fun to watch… He’s extremely talented.”

• Lynch was also asked whether Los Angeles Rams head coach Sean McVay’s approach to the preseason, in not playing any of his starters in any games, would become more commonplace. Lynch said that’s in play, as is the increase in joint practices, like the pair the 49ers had with the Denver Broncos:

“I think you could see that be a trend, and I think another trend will be you see teams doing a lot more of what we just did, going to Denver and working with another team, because then you simulate a little more of game action, still in a controlled environment,” Lynch said. “The things that go on in those things are pretty cool, particularly when you have a good relationship amongst the staff… You can get some looks that you really need.”

• Also, there’s no chance Jimmy Garoppolo will play in the fourth preseason game, no matter how bad it goes. “That’s off the table,” Lynch said. “I can’t see that happening.
• There was also the playful question about Hard Knocks, vis-a-vis the Antonio Brown saga with the Oakland Raiders. You can assume Lynch is fairly happy to have HBO’s cameras on the other Bay Area football team: “Every week when I get home and people are asking me about Hard Knocks I just say, ‘Thank you, lord,”” Lynch said.