Donald Rumsfeld was a lousy Secretary of Defense in the eyes of a lot of people, but he did make two contribution to the modern English language: “We know what we don’t know” and “We don’t know what we don’t know.”

Connection to the 49ers, Teach?? Well, as tempting as it is to go off on a historical jag about the Bush administration in this piece (remember, I do teach history and civics for a living here), Rumsfeld’s quote actually has some relevance to the 49ers. We know, for example, what their schedule is going to be this fall, who their head coach will be, where they’ll be playing, and (all things being equal) who their starting quarterback will be this coming year.

What we don’t know with absolute certainty is who will be playing the positions around Jimmy Garoppolo when he’s on the field, and who will be trying to stop the other team when he’s not.

So, for the sake of this piece, I’m going to predict (because we don’t know) who the starting defense will be for the Niners with the people we have right now. If we had to take the field with people on the roster right now, what would our defense look like?

Left Defensive End: Arik Armstead: This is his make-or break year, and I can’t image he won’t be well aware of that every time he hits the field. No, he is not the best choice as an edge rusher, but I don’t see an alternative at this point (barring an excellent draft choice). Ronald Blair has less to lose than Armstead and therefore won’t be quite as motivated, and Cassius Marsh doesn’t have the same discipline as the former Oregon Duck. Besides, Armstead has never struck me as anything but a trenchman, so sticking him in the linebacker corps doesn’t make sense.

Right Defensive End: Solomon Thomas: As a rookie, he made rookie mistakes (getting called offside a bunch of times, for instance), but let’s face it, the team doesn’t spend a first round draft pick on a player they will throw away the next year. Plus, given the way last year was going until Jimmy G showed up, you’d think every member of the squad would have been sour and sullen — but Thomas’ spirit never flagged. Get Thomas into the weight room, teach him to stay short in his blocking, and turn him loose. He won’t make the same mistakes again.

Left Defensive Tackle: D.J. Jones: When he was drafted in the 6th round, most observers were unimpressed, especially since Earl Mitchell was supposed to be the one who fit best in the defensive scheme. Well, Mitchell got himself hurt and didn’t put up any numbers worth mentioning; I can scarcely remember him playing a down all last season. But Jones was there all year. Jones is frighteningly strong, and he knows just how to block in the trenches: he starts low and then angles up to get an offensive lineman vertical. Plus, he operates from a huge base: he’s only 6’ tall, but he weighs 319 lbs. Try getting past him on short yardage and see where it gets you (hint: the ground comes to mind, with Jones staring down at you). Jones will have to compete with Mitchell and maybe Jullian Taylor for the spot, but I think he has the edge just on the basis of experience with this crop of coaches.

Right Defensive Tackle: DeForrest Buckner: This guy was elected Defensive Player of the Year by 49ers Insider 2 years ago, and I saw nothing but growth from him last season. If he can stay healthy and maybe learn to deal with double teams a bit better, there is absolutely nothing the former Oregon Duck cannot accomplish. Sheldon Day will keep him competitive in training camp, but I don’t see any chance he doesn’t win the starting position.

Left Outside Linebacker: Fred Warner: Okay, Eli Harold was at the top of the depth chart last year, but 3 sacks in 32 games is far from what the 49ers need at that position. Dekoda Watson did a fair job last season, but he is also getting long in the tooth and has never been an all-star anyway. John Lynch spent a 3rd round draft pick on Warner, who comes to San Francisco via BYU and has most of his experience at the outside spot (though some have predicted he’ll also swing inside from time to time).

Right Outside Linebacker: Brock Coyle: The Niners parted ways with NaVorro Bowman and Ray-Ray Armstrong in the last year, which has opened up opportunities for the former Seahawk to show fans and coaches what he can do. Coyle didn’t always get headlines, but he did get snaps and showed himself to be both tough and savvy about the modern game. It doesn’t hurt that he has a longtime relationship with Robert Saleh, who was a defensive quality coach in Seattle while Coyle was there.

Middle Linebacker: Reuben Foster (If He Is On The Team): Yeah, him. Leaving aside his off-the-field antics and his general immaturity, Foster genuinely scares opponents with his agility and his brutal way of tackling. Granted, he probably hits too hard at times, but I’ll take a battering ram over a dancer when it comes to a run defense any day. Besides, I don’t think the team is ready to abandon the first-round pick from last season just yet…unless he’s convicted of the domestic violence charges that might (or might not) be coming down the pike for him. Hey, Foster, listen to the Teach: even if you elude the judge this time, you are on notice. Grow the eff up. You’re not 16 anymore.

Cornerback: Akhello Witherspoon: I’ve been watching Jimmie Ward since he got to San Francisco, and I’ve been waiting for him to be the defensive superstar that he was hyped to be. Hasn’t happened. What I’ve seen is unfulfilled potential, injuries, and middle-of-the-road competence; what I wanted was broken-up passes, interceptions, and incompletions. Witherspoon is younger, he is more aggressive, and he is faster than Dontae Johnson or Greg Mabin. Which brings us to the shock-acquisition of the year…

Cornerback: Richard Sherman: Put the abuse from the Seattle Chickenhawks in the past — he’s now going to bad-mouth other teams on our behalf. Sherman is a legit badass: he has been selected to the Pro Bowl four times and voted All-Pro four times, including three times to the first team. Sherman has also broken the hearts of Niners fans a few times, including the “Immaculate Deflection” in the 2014 NFC Championship game. He got fed up with Seattle when they yielded the Team of the Eon title to the Patriots, and the feeling was probably mutual. Let the guy do his job and earn his pay. You don’t even have to like him. Promise. Just don’t boo him.

Free Safety: Tavarius Moore: Eric Reid was allowed to leave the team without the Niners putting up much of a struggle, and the Niners promptly drafted Moore out of Southern Mississippi in the third round. A rookie, taking on the starting position? Hey, the guy only played 2 seasons in college and posted 104 total tackles with three interceptions. NFL luminaries like Mike Mayock and Lance Zierlein have been raving about him — and he might even be able to put in some downs at cornerback. Do you really want to cross your fingers and hope Chanceller James can do as well? Me either.

Strong Safety: Jaquiski Tartt: The Saleh defense enabled Tartt to line up closer to the line of scrimmage than a safety normally would, which has allowed him to show off his speed. Tartt has managed to pull down 82 tackles in 20 starts, and he has an impeccable sense of timing: he doesn’t get called for penalties much, and he knows exactly when to hit a wide receiver to either disrupt passes or cut the Yards After Catch to a minimum. I want Adrian Colbert to continue developing and bring out the best in Tartt, but for the sake of effectiveness I want the Samford graduate to be on the field in Week 1.

So there it is. A few rookies, some savvy veterans, and a thirst for violence. Of course I don’t know what the future will hold, I don’t know what Kyle Shanahan is thinking, and I don’t know what I don’t know.

But then again, you don’t know what I don’t know either. Or is it that you don’t know what you don’t know?

Well, you never know!


Featured image credit: Michael Zagaris — Getty Images