Pressuring the quarterback is critical to defensive success and the Lions didn’t come close to generating enough in 2017. The team finished 20th in the league with 35 sacks, and according to Football Outsiders, 24th in pressure rate, making the quarterback uncomfortable on just 29.2 percent of passing plays. Pressure can come from a variety of ways, from blitzing to stellar coverage forcing the quarterback to hold on to the ball, but the primary source should be a team’s defensive line, particularly the edges. That’s an area the Lions must improve this offseason, but it appears unlikely to come via free agency. The Lions already made the most important free agent move they could make, given the alternative, using the franchise tag to retain defensive end Ziggy Ansah. The cost-for-production rate isn’t ideal, given Ansah’s inconsistency the past two seasons as he’s battled through a number of injuries, but it was a necessary trigger for general manager Bob Quinn to pull, even with a price tag north of $17 million for the 2018 campaign. That’s because there’s not a viable replacement on the open market, which overvalues marginal talent because of the importance of the position. And there’s little reason to believe the Lions can find a plug-and-play replacement for Ansah in the upcoming draft, with the top edge rushers likely long gone by the time the team is on the clock at pick No. 20. In addition to Ansah, Detroit is almost certain to exercise the exclusive rights option for Kerry Hyder, who missed last season with an Achilles injury. If he returns to form, having racked up a team-high 8.0 sacks in 2016, it would provide a big boost to the group. That’s important given this year’s market is setting up to consist of a number of mid-tier players, past-their-prime veterans and cap causalities.