Defensive technique question for Clay, DD, Matt or anyone who has input

Two things I see a lot from our defensive players that I wonder what coaching or technique has influence in changing.

Getting off the blocker. It seems that our defenders often are in good position, if they could get off their blockers. and the ball carrier just runs by them untouched often through the line of scrimmage, thus the abundance of long gainers given up by the defense. I know the d-line is to pick off blockers so that the backers can clean up the play, but it sure seems that across the board we are wrestling with the blockers while the play is running past us.

Tackling: I see some teams where the defense aggressively attack the call carrier, often times stopping them in their tracks and even knocking them back from time to time. It seems to me that our tacking technique must be different where we appear to grabbing the ball carrier or even attempting to catch the ball carrier. We seem to often see the offensive player falling forward. I know from an injury prevention standpoint, the way we tackle likely does not lead to as many injuries, but it sure seems to shorten the field for the offense when one adds 1-2 to yards after contact.

I am not looking for a fall guy or guys, just noticing things that appear to be opportunities for improvement.