Last year, the middle of the Browns defense was a roller coaster. While playing the 4-2-5 may be a good defensive scheme for an ultra passing club, for a team that can gash with a good runner this defense has its issues.
For one, there isn’t a true middle linebacker but rather two outside linebackers lined up in the middle-to-outside gaps. A savvy defensive coordinator can read this and design inside runs which can shield both backers, and if the offensive line can do its job at the line of scrimmage before you know it the running back has skipped two levels and is now out in the open.