In general, NFL inside linebackers have become smaller, faster and quicker over the years, a concession to the greater emphasis on the passing game. Inside linebackers are no longer just asked to be run stoppers. The ability to contribute in the pass rush and in coverage are also important as more and more offenses throw the ball with more frequency than they run it.
In 2017, four teams threw the ball at least 200 more times than they ran it. As a result, the line between inside and outside linebackers has been blurred in many defenses, especially with the increased use of sub packages.