How is 3 sacks "as effective at getting to the QB" as Chaisson's 7.5? Chaisson was a starter. Greenard would be coming off the bench as he's not an upgrade over Landry or Jones.
From Pro-Football-Reference.
Chaisson had 7.5 sacks and 18 QB hits on 400 Pass Rushing snaps. 1 sack or QB hit every 15.7 snaps. 12 missed tackles
Greenard had 3 sacks and 11 QB hits on 270 Pass rushing Snaps. 1 sack or QB hit every 19.3 snaps. 11 missed tackles
Dre'mont Jones had 7 sacks and 24 QB Hits on 507 Pass Rushing Snaps. 1 sack or QB hit every 16.35 snaps. 3 Missed tackles
To me, what Jones did last year is more impressive since he did it while playing on 2 different teams. Jones is the upgrade. Greenard is not.