Earl's middle linebacker-esq play recognition is sorely missing. His ability to see a run coming and either a) blow up the play or b) blow up the blocker to let the cavalry make a play is incredible. He also knows when to leave his zone to interrupt a developing deep pass which many NFL safeties don't know how to do.
His absence is very noticeable on the slew of big plays we generally haven't seen the past 4-5 years. Defense played mostly fine outside of a handful of BIG plays and I think with Earl back there, they either don't happen or would be less damaging (Terrell tripping torched Lane would not have happened, or if it did Earl is right there to limit). It's incredible what he's allowed the defense to do since he got here, I can't think of any other defense who just leaves someone on an island while they simultaneously run the show.