Vikings coach Mike Zimmer sat with the NFL's reigning No. 1 defense in February and wondered, "Do we need to do something different, even though they're converting one third down per game?" Zimmer's honest offseason assessment led to the eventual answer of yes, get more pressure on the quarterback — especially up the middle.

Enter DT Sheldon Richardson, a free-agent prize signed this offseason to a one-year, $8 million contract lined with another $3 million worth of incentives. That's a lofty investment for a defense that was as close to perfect as any in the league last season.

The Vikings believe Richardson, 27, can make them better; Richardson, a former first-round pick who was shipped from the Jets to the Seahawks a year ago, feels the same way — especially about respected Vikings defensive line coach Andre Patterson.

"I do feel like he can take me to the next level," Richardson said of Patterson. "Redefine my hands and make those pressures turn into sacks."

Sacks were harder to come by for the Vikings defense as last season progressed. The production was nearly cut in half, from averaging 2.7 sacks in the first 11 games to 1.4 in the final seven games of the season and playoffs.

Look deeper and you'll find just 6½ of the Vikings' 40 sacks came from defensive tackles. That's not ideal for Zimmer's scheme, which was in place when Geno Atkins became a quarterback's nightmare as a tackle for four seasons in Cincinnati.

The Vikings have little doubt Richardson can provide an upgrade up the middle.

"He's a guy that can go in there and bring pressure when we need him to," defensive end Danielle Hunter said. "It's going to be a plus for the defensive line and defense, because it's a part of our defense for the three-tech [defensive tackle] to bring pressure."

Richardson was a top-20 interior pass rusher for the Seahawks last season with 36 total pressures (hurries, hits and sacks), according to Pro Football Focus. But he had just one sack, meaning he lacked "the vanity and the numbers," Richardson said, that often accompany a highly coveted free agent.

He could become one of 2019's top free agents if he reaches the ceiling the Vikings expect. Along the way, Richardson also would make life easier for the Vikings' top two pass rushers off the edge in Hunter and Everson Griffen.

"It's all about whenever you bring pressure to a quarterback's feet, it stops him from stepping into his throws," Hunter said. "It makes him hold the ball longer. It gives us time to go around the edge and beat our guys, make moves and just get to the quarterback."