I guess I look at this a little different. We aren't going to replace McDonald, Rose, Kolar or Purdy. But we will have individual players step in a different way from our current studs or we will see the position group en masse step up.
On the DL bringing back Lee & Singleton should be a solid start in the middle. Zach Petersen coming back would be huge, he has a great motor. IMO he could significantly increase his draft stock coming back for 2022. The staff has also recruited a number of DL in the last 2 classes that hopefully a couple will be ready to step up- Wilson, Suttle, Onyedim, Brown, Peterson and Gray.
Also we could see the LB position group be more active in rushing the QB.