Back in 2014, when Mike Zimmer was a veteran coach but a rookie head coach with the Vikings, he hired Norv Turner as his first offensive coordinator.

The conventional praise was that Turner was also a veteran coach, and had been a head coach before — giving Zimmer a good sounding board and allowing the head coach with a defensive background to worry less about the offense.

In some cases, letting your coordinators coordinate can be empowering. But with Zimmer and Turner, the relationship was off from the start. Zimmer was probably too hands-off in his first season. And has he tried to assert his offensive philosophies more in 2015 and 2016, tension grew to the point that Turner resigned midway through the 2016 season.

"It just got to the point where I didn't think it was going to work with me. So I removed myself," Turner said at the time. The Vikings ended up with a different offensive coordinator at the start of every season going forward in the Zimmer era.

That brings us to Kevin O'Connell, younger than Zimmer by more than two decades (36 vs. 57) when taking over the team and also a first-time head coach. O'Connell's background skews heavily on offense, and he has hired a veteran defensive coordinator (Ed Donatell) to run that side of the ball.

As I talked about on Friday's Daily Delivery podcast, I liked Donatell's energy and answers in his introductory news conference Thursday. But it is also very important that O'Connell avoids the same mistake Zimmer made in focusing too much of his energy on one side of the ball.

O'Connell assuaged some of those concerns with encouraging words on Thursday when talking about Donatell, showing that he has given extensive thought to what he wants in a defense.

"When you're an offensive head coach and you've coached in this league long enough ... you really start thinking about it from a standpoint of what do you not like to play against? What's the hardest defensive scheme to play against? What keeps you up at night as you game plan as an offense? Guys like Ed Donatell," O'Connell said. "He's primed to take over our vision of how we want to play defense with the Vikings."

As busy as O'Connell is now, though — assembling a staff, sifting through the roster, moving his entire life to Minnesota — it will only intensify once actual football is being played.

Can he maintain the right balance of paying attention to a side of the ball that falls outside his main line of expertise while still letting Donatell do his job?

My guess is the answer is yes. But we've seen the consequences if the answer is no.