He was around top five in sacks between 2010-2013 (40.5), has never been a big tackle producer (30ish).
He only had 1 sack last year, but missed the first 2/3 of the season. Bizarrely, the Rams led the NFL in combined sacks for 2012-2013, than set a record for futility with only 1 sack through the first five games. They finished with 40 (34 of which were in the last nine games, which would project to 60 over 16 games). During the season they began starting Aaron Donald, who had 9 sacks, was Defensive Rookie of the Year and some stat sites graded him as the top DT in the league, higher even than Suh, just made the richest defensive player in NFL history. They also traded for former #7 overall safety Mark Barron, and used him extensively in their big nickel package. Long will be playing in a DL in which the top five (including ex-DET DT Nick Fairley) were taken in the top half of the first round - not sure if unprecedented, but would have to be rare.
In dynasty, Long is about 30, and is the second highest paid Ram after Robert Quinn, so not a lock to remain with the team beyond this season if he doesn't play more like he did from 2010-2013.