One thing that helped me was a healthy mix of both man and zone, but also (with the giants playbook which has 2 LBs in on Dime) I double cover the inside TE or WR with the original blitzing LB. This has helped with the TE always getting open cheese and it also seems to help with slants Bc depending on that WR’s route the double cover will sometime impede that slant route and cause the QB to go somewhere else. I still give up a fair share of slants but not like I used to.