It happens to every team, every season. The week they are eliminated from the playoffs, and the following weeks remaining in the season end up being filled with roster changes and trips to the Injured Reserved. That is why it is no surprise to see that the Bears put two of their starters on the Injured Reserved on Tuesday.
Long has had a bad track record of injuries recently. Last season he ended the year on the IR, and that injury lingered into training camp and the regular season of 2017. Long missed a game a couple of weeks ago in a bit of a surprise, but it has been clear all season that this was not Long at his best.