Paul Guenther and Mike Zimmer last worked together eight years ago in Cincinnati, when they'd built up a defense that would help both men go on to bigger jobs in the NFL. They refined the Bengals' version of the double-A gap blitz package that became a hallmark of the scheme, and put together three defenses that ranked in the top 10 in both yards and points allowed during their final three seasons together on Marvin Lewis' staff.

Now that Zimmer is trying to reform a defense he called the "worst one I've ever had" at the end of 2020, he's hoping a reunion with Guenther can help.

The Vikings' new senior defensive assistant has been a defensive coordinator for seven seasons, dating from him replacing Zimmer in Cincinnati in 2014 to his three seasons with the Raiders before he was fired in December. He joins the Vikings as the latest of Zimmer's confidants, charged with improving a young group that faltered under the weight of inexperience and injuries during a 7-9 season.

"Having the opportunity to learn from Mike and build this system up to where it is today, just really excited to get back with him," Guenther said on Thursday. "A guy I'm real familiar with: his core values, the way he runs the team, the way he runs the program here. Real excited to be joining forces again."

The team introduced Guenther and former Alabama defensive backs coach Karl Scott — who replaced Daronte Jones after he became LSU's defensive coordinator — on Thursday as the latest pieces of a defensive staff that will bring back co-defensive coordinators Andre Patterson and Adam Zimmer, as well as assistant defensive line coach Imarjaye Albury and assistant defensive backs coach Roy Anderson. The Vikings also hired former Wofford defensive coordinator Sam Siefkes as a defensive quality control assistant.

Together, the group will work with a defense the Vikings hope can improve quickly, as Danielle Hunter and Anthony Barr return from season-ending injuries, Michael Pierce looks to return from a COVID-19 opt-out and a young secondary gets another year of experience.

"These guys obviously got thrown into the fire some last year with some injuries and some guys opting out," Guenther said. "So these guys have a lot of experience, and I just like the way they play the game. They play relentless. They're fast to the football. They understand what they're doing, and hopefully throughout we have an offseason and we can get them better at doing those things. So again I'm just excited to be a piece of this moving forward."

Scott, who'd been at Alabama the past three seasons, had been set to take over as the defensive coordinator at Louisiana-Lafayette until the Vikings job opened up. His work with Nick Saban's pattern-matching coverage schemes could translate to Minnesota, where the Vikings have employed similar concepts under Zimmer.

"At the end of the day, it's football, and we're all doing pretty much the same thing but calling it different things," Scott said. "When you look at the film of Alabama and you look at Coach Zimmer's defense, honestly there are a lot of things that marry together. So I'm definitely looking forward to being a part of this and getting back to where we used to be."

Guenther's role will be more nebulous than the last time he worked for Zimmer; the head coach still calls the plays on defense, while Patterson and Adam Zimmer will keep their current roles. The Vikings first brought in a senior defensive assistant last year; Guenther replaces Dom Capers in that role.

"From what I understand, it's helping out all three levels of the defense," Guenther said. "I've been able to coach those three levels throughout my career. Maybe help out some things situationally game day, packages, whether it'll be situational packages, just the overall details of the scheme and the players within it. We have to be looking for guys who can fit our scheme, whether it be in free agency or the draft and those type of things."

He reunites with his old boss before a pivotal season; the Vikings are basing their belief in a rapid turnaround on the idea their defense can quickly regain its form.

"You get a chance to do it on your own, learn things on how to call a game," Guenther said. "Hopefully I can help [Mike], I can help Andre, Adam, those guys on game day get to the core of what we need to get done."