SANTA CLARA Womens Patrick Willis Jersey , Calif. (AP) — The San Francisco 49ers still aren’t certain about the availability of their top two running backs for Sunday’s game against the Los Angeles Chargers.Matt Breida, among the NFL leaders in rushing, and Alfred Morris both were limited in practice Friday and are listed as questionable. That’s an obvious concern for an offense preparing for its first full game without franchise quarterback Jimmy Garoppolo, who suffered a season-ending knee injury last week against Kansas City.Breida hyperextended his right knee while planting to make a cut in the first half against the Chiefs. He returned later in the game, but the second-year back out of Georgia Southern hasn’t shown considerable improvement in practice since then.“He’s been up and down a little bit this week,” coach Kyle Shanahan said Friday. “He got a little bit more (practice time Thursday). We kept him limited just trying to manage the wear and tear. But ‘questionable’ is better than ‘doubtful,’ so we’re hoping it works out.”Morris also is slowed by a knee injury. While he brings power running between the tackles, Breida is the game-breaking threat. His 274 yards are tied for second in the league with the Dallas Cowboys’ Ezekiel Elliott behind the Rams’ Todd Gurley.But Breida has carried the ball just 32 times, giving him an average of 8.6 yards per carry that’s best in the NFL.His emergence has helped soften the blow of the 49ers losing expected starting running back Jerick McKinnon to a torn ACL shortly before the season opener.Breida had said he initially feared a much more serious injury.“It’s gonna be a game-time decision,” Breida said of his availability against the Chargers. “I gotta feel comfortable. I’m not at 100 percent right now. .“I know I have to be smart, too, and understand that if I’m not gonna be able to cut off it and not gonna be able to run, then why go out there and get myself hurt and hurt the team at the same time?”San Francisco’s depth in the secondary also remains an issue. Strong safety Jaquiski Tartt is doubtful and is likely to miss his second consecutive game with a shoulder injury. He didn’t practice Friday.Antone Exum would start in Tartt’s place; Exum made nine tackles with a sack and a forced fumble against Kansas City.“Exum’s here for a reason,” Shanahan said. “I thought he got a lot better as the game went. I think he made some mistakes early in the game, and I think once he played a little bit more, it slowed down for him.”Free safety Adrian Colbert is questionable with a hip injury. Should he not be available Sunday, rookie D.J. Reed likely would take his spot.The 49ers already were without veteran cornerback Richard Sherman, expected to miss at least two games with a strained calf.NOTES: Receiver Marquise Goodwin (quad) and right guard Mike Person (knee) participated fully in Friday’s practice and are expected to play against the Chargers. Reserve guard Joshua Garnett (toe) remains out. DENVER (AP) — We’ve been hearing it for months: The 2018 NFL draft is all about the quarterback.The quarterback conundrum is more like it.“You can go around a room and probably get four or five different opinions on how they should be stacked.”That’s a quote from John Elway, Denver Broncos general manager and headliner of the pre-eminent 1983 QB class that featured six first-round selections and produced three Hall of Famers.There’s no consensus top QB this year like there was with Andrew Luck or Cam Newton a few years ago. Every one of this year’s “Big Four” — USC’s Sam Darnold , Oklahoma’s Baker Mayfield , Wyoming’s Josh Allen and UCLA’s Josh Rosen — can find their names atop somebody’s mock draft this week and almost certainly first on somebody’s draft board Thursday night.What this year’s quarterback crop lacks in clarity it makes up for in complexity.Louisville’s Lamar Jackson , Oklahoma State’s Mason Rudolph , and Senior Bowl star Kyle Lauletta of Richmond are also hopeful they’ll hear Roger Goodell call their names early. Throw in Washington State’s Luke Falk, and maybe it’s one of these “Little Four” quarterbacks who might ultimately end up as the gem of this year’s draft.Sort of like sixth-rounder Tom Brady in 2000 or third-rounder Russell Wilson in 2012.Should six quarterbacks go in the first round, as many suspect, it would tie the `83 standard when Elway, Todd Blackledge, Jim Kelly, Tony Eason, Ken O’Brien and Dan Marino were selected.If quarterbacks go 1-2-3, it would match 1999’s group in which Tim Couch, Donovan McNabb and Akili Smith were the first three players off the board a year before Brady went 199th.There’s no clear-cut, surefire top pick quarterback in this year’s draft because all of the prime prospects have at least one key drawback.So, all of those owners, GMs, scouts and coaches scratching their heads for months will soon be crossing their fingers if they bypass Saquon Barkley, Bradley Chubb, Quenton Nelson, Denzel Ward, Minkah Fitzpatrick, Derwin James and Tremaine Edmunds to dive into the deep quarterback class , which could make or break a franchise’s fortunes.Every year, quarterbacks rise to the top of the draft, pushing value down the board to teams who already have theirs. Fifty-six quarterbacks have been drafted in the first round since 1996, the last draft featuring no first-round QBs.“This quarterback draft, like every draft, drives the top end of this thing,” NFL Network analyst Mike Mayock said. “I’m always amazed — and maybe I shouldn’t be — but last year, three of the top 12 picks were quarterbacks and all three were trade-ups on draft night. The year before, the Rams went all the way up to one to go get (Jared) Goff. The Eagles went from 13 to eight to two to go get Carson Wentz. It’s a quarterback-driven league. I think it’s going to be a crazy eight, 10, 12 picks, so many permutations of the quarterback conversation.”Underscoring the importance of the so-called franchise quarterback, the Texans averaged 35 points a game with DeShaun Watson last season and 13 without him; the San Francisco 49ers went from 17 points a game to 29 under Jimmy Garappolo, who won all five of his starts.And yet …Case Keenum Womens Malcolm Smith Jersey , who wasn’t even drafted, took the Vikings to the NFC championship game. Blake Bortles, a top-10 pick but, in Mayock’s words, nobody’s idea of a “high-level franchise quarterback,” took the Jaguars to the AFC championship contest.And backup Nick Foles, a third-rounder, outdueled Brady to win the Super Bowl for the Eagles.“Is that an aberration or a trend?” Mayock wonders.A look at the top quarterbacks in 2018 and the hazards that accompany the hype:SAM DARNOLD, USC: Ball security.Darnold threw 22 interceptions and had 20 fumbles in his two seasons with the Trojans.“The No. 1 priority of a quarterback is to protect the football. I’m aware of that, and I’m aware how much I turn the ball over and that it’s not OK,” Darnold said. “I’ve been addressing it this offseason. I’ve been working on keeping two hands (on the ball) in the pocket at all times. The only time I let go of the ball is to throw it. That’s something I’ve really been working on — and also keeping it tight whenever I tuck it and run.”JOSH ALLEN, Wyoming: Accuracy.The rocket-armed Allen hopes his spectacular combine showing and pro day performance showed teams that his 56 percent completion rate at Wyoming shouldn’t scare them away.“I’m extremely confident in myself,” Allen said, “and we’re working on it and there’s no doubt in my mind we’ll figure it out.”BAKER MAYFIELD, Oklahoma: Undersized.Mayfield is a shade over 6 foot, and that’s usually a deal breaker in the first round.“Height doesn’t matter,” Mayfield declared at the NFL combine. “You see guys like Tyrod Taylor, Drew Brees, Russell Wilson, they’ve proven that it doesn’t matter. If you want to say anything else, I’ve got three years of tape you can watch. I think I had fewer batted balls at the line of scrimmage than any other guy here — and I’m pretty sure I’m the shortest guy, too.”JOSH ROSEN, UCLA: Durability.A shoulder injury limited Rosen to six games last season, and he’s had concussions. Furthermore, he’s had to answer questions about his dedication to the sport. Many have wondered whether the strong-armed, free-spirited QB is the next Aaron Rodgers, a cerebral pick-you-apart passer, or the next Colin Kaepernick, who will ultimately focus more on social issues than football, especially if he can’t stay healthy.“I love football with all of my heart and soul,” Rosen insisted. “If I didn’t, I just don’t think I wouldn’t been able to make it through the grind of college.”LAMAR JACKSON, Louisville: Mechanics.Bill Polian suggested Jackson’s off-the-charts athleticism might make him more valuable as a wide receiver, but Jackson dismissed that notion: “No sir, I’m a quarterback.”And a darn good one, Mayock insisted.“He’s the most exciting athlete in the draft,” Mayock said. “I think somebody in the first round is going to make a philosophical and schematic commitment to this kid and change what they do offensively.”MASON RUDOLPH, Oklahoma State: Mobility.Mayock said for a 6-foot-5, 240-pound quarterback, Rudolph has “fairly average arm talent” and too often can’t escape the big hit, which could make him the next great college quarterback to get steamrolled in the pros.“In today’s NFL, you’ve got to have some escapability, some ability to buy some extra time,” Mayock said. “I think he struggles with that a little bit. When he’s got time with clear feet and clear vision, he can drive the ball, and I think he’s the best deep ball touch and accuracy thrower in this draft. So I’m very bullish on this kid. I like the kid.”KYLE LAULETTA, Richmond: Health.Winning offensive MVP honors at the Senior Bowl should squelch concerns about his college competition and working through four offensive coordinators with the Spiders. He also sees a silver lining in his torn ACL before his senior season, when he had to sit out spring ball.“Mental reps are huge. It sounds clich?, but when you’re in the NFL, if you’re a backup or not the No. 1 guy, you’ve got to get better and you’ve got to improve somehow. So learning from those who are taking the reps and putting yourself (mentally) in that position, that’s what I did,” Lauletta said.12<button class="view-gallery">View Gallery</button> Gallery:Cowboys’ biggest draft steals of the Jerry Jones eraAP