There were red flags when Brady Hoke arrived as Oregon’s defensive coordinator before last season. One issue was that Oregon had enjoyed success with a 3-4 defense and had been recruiting big, tall defensive ends to play in it. But Hoke was installing a 4-3 system that asked different things of his line. Another issue: The playbook Hoke brought with him was compared to a Harry Potter book because of its size and scope.

There were also questions about what exactly Hoke’s defense would be, since he hadn’t been a defensive coordinator in many, many years. It turned out to be the 4-3 Under defense that the Wolverines employed in his time as head coach in Ann Arbor. In the Under front, the third LB (the Sam) has to be big and strong enough to play on the edge, yet the demands of modern spreads also requires that he be able to play in space.

Hoke’s Under system was successful at Michigan, but it was in need of tweaks towards the end to handle the growing prevalence of the spread offense in the Big Ten. In fact, Michigan converted to the 4-3 Over the year before Hoke was fired.

But Hoke brought the Under with him to Eugene, where spread offenses litter the schedule every year. What Hoke did at Oregon didn’t work. The Ducks went 4-8 and finished 119th in Defensive S&P+, giving up 42.6 points per game.

So newly acquired head coach Willie Taggart hired away Colorado defensive coordinator Jim Leavitt for more than $1 million a year. At Taggart’s introductory presser, UO’s president only gave him one piece of advice: to hire a great defensive coordinator.

Leavitt now has quite the job ahead of him in restoring Oregon’s defense to a level that can once again take advantage of the Ducks’ annually great offenses. (The Ducks offense should be good quickly under Taggart’s leadership.)

Oregon and Colorado have been a tale of two defenses.

Mike MacIntyre was well regarded when he arrived at Colorado in 2013 from San Jose State. But the pro-style offense and hard-nosed defense he intended to bring to Colorado were both scrapped in favor of a dynamic, up-tempo spread and a new, 3-4 defense. Colorado’s defense was bad when MacIntyre arrived, but within two years, new coordinator Leavitt fixed things up just fine.

Compare Colorado’s improvement post-Leavitt to Oregon’s collapse after Chip Kelly (and maybe more importantly, Nick Aliotti) departed the program.

The main goal, and perceived challenge, for Hoke was to get the Ducks playing tough, sound football once more. The 2015 unit was horrendous and regularly beaten due to assignment errors and unsound play. Hoke’s 2016 squad was often fairly disciplined and tough, but it wasn’t sound, often due to outdated schematics.

A fantastic example is Oregon’s play against Davis Webb and the Cal Bears’ air raid offense. Hoke rolled with his base 4-3 defense against the Bears’ spread formations, which meant freshman Sam linebacker and team sack leader Troy Dye (No. 35) was often playing out in space.

Here’s how that play looked drawn up on the chalkboard:

To overcome the issue of rolling with three linebackers against a four-receiver formation, the Ducks spread them the width of the field with safety help over the top. This often worked. Oregon held Webb to 325 yards on 61 passes: only 5.3 yards per attempt, a number that would normally suggest you’re demolishing an air raid team.

Not this game, because Cal’s two main backs, Tre Watson and Khalfani Muhammad, combined for 302 more yards on 51 carries, good for 5.9 yards a pop. Flooding the field with big defenders and then asking them to navigate space left Oregon vulnerable at the point of attack in the run game.

On the play here, Oregon has shaded free safety Brenden Schooler (No. 43) and middle linebacker A.J. Hotchkins (No. 55) over to the trips-receivers side, leaving weak-side linebacker De’Quan McDowell (No. 54) alone in the box.

There’s so much that’s unsound about this approach, it’s frankly quite shocking. Is McDowell supposed to defend both the field A-gap and the boundary B-gap? Is the boundary DE supposed to force the ball back inside? His aggressive play up the field sure put McDowell in a bind when the B-gap, between the left tackle and guard, was expanded by his absence from the line of scrimmage.

The last time I saw a defense attempt an approach to run defense this outdated against an air raid team, Tavon Austin was running for 344 yards on Oklahoma.

Meanwhile, the Buffaloes were making a leap in Year 2 with Leavitt, a year in which he was confident enough in his players’ understanding of fundamentals to move from the 4-3 to the 3-4. With multiple guys across the defense that had earned Leavitt’s trust as pure football players in 2015, the Buffs were able to embrace the flexibility of the 3-4 to employ lots of different tactics to force offenses to play left-handed.

The Colorado front three of nose tackle Josh Tupou and ends Jordan Carrell and Samson Kafovalu was a very stout unit — all seniors and all willing to battle double teams and maintain the line of scrimmage on behalf of inside linebackers Kenneth Olugbode and Rick Gamboa.

The way in which USC completely fails to move the line of scrimmage here is rather stark. But that was normal for the Buffs, playing with a pair of inside linebackers that were flowing to the ball fast and confidently behind such a sturdy group in front of them.

The secondary was equally brilliant, as recently became evident from the NFL combine. With Ahkello Witherspoon, Chidobe Awuzie, and Tedric Thompson on the field the Buffs had a lot of coverage options for adjusting to various opponents. One of their more effective schemes was a fun combination of cover 2 and ultra-aggressive quarters that they’d employ to help stop the run:

On the chalkboard, you can see how they leveraged the talents of the secondary to set themselves up to lock down the Cardinal’s favorite players and plays:

The Buffs are playing cover 2 over the TE side, with Awuzie (No. 4) stationed there, where he can be active on the perimeter. Awuzie was third on the team in tackles and had four sacks, because they’d often put him in the boundary or over the slot so he could be involved against the run. Witherspoon (No. 23) is out wide in press coverage, while Thompson (No. 9) is helping the Sam linebacker bracket the slot in cover 4.

The key to the cover 4 coverage over the slot is that the Sam, staffed here by 6’1, 215-pound DB Ryan Moeller, can be aggressive on a run read. That’s because Thompson is athletic and skilled enough in coverage to pick up the slot if he attacks the edge. Moeller (No. 25) was basically a specialist for Colorado last year, forcing the edge and serving as a tackler in space, and he was able to be very aggressive and useful in their run defenses because Thompson was behind him.

The Buffs would mix in cover 3 and other schemes and vary who played where to pull off tricks like bracketing an opposing team’s No. 1 receiver while locking down the No. 2 in man coverage, a la Bill Belichick’s Patriots. Such are the luxuries of life when you have a sound football team stocked with skilled veterans.

At Oregon, Leavitt will have chances to mold the defense over time.

The two best players for Oregon this past year might have been freshmen Dye (Sam linebacker) and Schooler (free safety). This is unquestionably a good thing for the Ducks, because Leavitt is going to groom the younger players on this squad into football players and then go from there.

Dye will be an interesting player for Leavitt to utilize, as his skill set didn’t exactly exist on the 2016 Buffaloes. Colorado did have Jimmie Gilbert, a 6’5, 230-pound outside backer who Leavitt used to patrol the boundary and blitz the edge. But Oregon has two such players, Dye and Justin Hollins (6’6, 230), both returning. I don’t think Leavitt will leave Dye out in space on the far hash mark to defend screens as Hoke regularly did, particularly if he proves to once again be the best pass rusher on the team.

Schooler’s specialty last season was erasing the mistakes of his teammates with his downhill fills and good angles in the open field. That’s a fairly universal skill for a safety and will surely prove useful again this coming year, as the Ducks work through a new defensive scheme. But Leavitt may involve him in the run fits more than Hoke did.

The defensive line was basically recruited to Leavitt’s scheme and should round into form sooner than later, but the Oregon defensive backfield is filled with upperclassmen that have been through bad campaigns. The fix there may take longer for Oregon, but there’s still reason for optimism.

If the Ducks can arrange their talent in a way that maximizes it, we’ll see a better defense than we’ve seen the last few years in Eugene. That’s how it looked in Boulder, after all.