When we talk about improving as a football team year over year, it's not just limited to the improvements the players make year to year or the improvements gained on the roster from one year to the next.

There's always a self evaluation that goes on among the coaching staff, too. Detroit Lions offensive coordinator Jim Bob Cooter takes himself through that practice every offseason.

The Lions had the seventh best scoring offense in the NFL last season, but Cooter expects himself to be an even better play caller in 2018.

"I plan on improving personally every year," Cooter said earlier this week. "And every year, I've learned at this point not to think that I have all the answers or even most of the answers.

"I'm getting better every year. Every year I figure out something that I go, 'Man, a year ago I didn't see it that way and now I do.' I think I understand it better. But this is a complex league. You've got to stay fluid."

The evolution of Cooter's scheme has been evident since he took over as offensive coordinator for Joe Lombardi midway through the 2015 season. The way his passing attack has evolved from a short, timing attack in 2016 to one of the best downfield attacks in the league last year is proof Cooter isn't afraid to evolve and adapt alongside his personnel.

"I'm studying a million things," he said. "Trying for these little one percent improvements here, there, everywhere. And it could be something that's obvious to you guys, to the fan at home. It could be something that's totally not obvious, but it may have a big impact at a certain moment."

One area Cooter has no-doubt spent a lot of time on this offseason is the overhaul of his rushing attack. The Lions ranked last in the NFL in rushing last season, and general manager Bob Quinn invested heavily on that portion of the offense. He drafted interior lineman Frank Ragnow with their first pick in the draft, selected a running back (Kerryon Johnson) and a fullback (Nick Bawden) after that, and signed veteran running back LeGarrette Blount in free agency. The Lions also have a new offensive line coach in Jeff Davidson.

"You're always trying to look at the previous year and sort of improve and get better," Cooter said. "I'm sure we'll change plenty and I'm sure there will be a lot where you guys will look out and see some similarities.

"We're going to try and get better. Think we've identified a couple ways we think we can do that. Obviously, I'm not going to tell you anything about that. But that's the process everywhere. It's really flawed on my part if we stay stagnant. We've got to adjust to the players, we got to adjust to different things going on in the league and hopefully we're doing that."

Cooter talked about his goal of getting at least one percent better in all areas, and that how sometimes it's the small adjustments, the ones that might fly under the radar of most observers, that might make the biggest impact.

The offseason affords coaches like Cooter the time to not only study their own game film, but look at what other teams are doing, and study any trends going around the league that could be adopted into what the Lions do on offense.

"There's a bunch of tape out there, there's no shortage of tape to study," Cooter said. "Every play's its own little experiment. What happened on that play? Did it work? Did it not work? And why?

"The more we can figure that out, hopefully the better position we can put our players in and at the end of the day those guys on the field are doing this whole thing. We try to get rid of the bad calls and let them go do the good calls."

Cooter even gave an example of what he's talking about in terms of the subtle changes that might fly under the radar but could have a big impact at the right moment.

"Some of them are such minor details," he said. "It's, 'Boy, I've thought forever that this route was a 12-yard route or these other people they run it at 14, that can't be right. And alright, let me spend two hours watching those routes and oh, 14 was right. Okay.'

"So, it's little boring things like that. It will never show up, but just trying to get better. Trying to do my job better. I walk in the door one day at a time. Put together some good days and see where that leaves us."