Jaren Jackson Jr. is one of the best defensive players in the NBA, so seeing a drop-off in production when he is off the floor isn't earth-shattering. However, the Grizzlies' defensive rating difference was a significant gap when he was on the floor with Zach Edey vs when he was off the floor last season with Edey.
Memphis had a defensive rating of 109.6 when Jackson Jr. and Edey shared the floor, which would've made the Grizzlies a top-two defense if that number remained for the team entirely. The Grizzlies finished last season with a defensive rating of 113, which ranked 10th in the NBA, and was their defensive rating in lineups that included Jaren without Edey.