I have to agree.
You can get to the QB a lot with a DE or DT.
You normally have time to do one move. If it works you will get to the QB. If the coverage is good or the routes are long or you have a very fast DL you will get a sack. Most times you will get a hurry. But the pressure is there.
If you can get consistent pressure the CPU will start throwing early and INTs. Many of my sacks are when I play the Safety (they are rarely in the right position otherwise) and help the coverage. I usually only play the DL on passing downs.
However, you can blitz but if you simply line up a zone blitz the CPU OL is not going to be confused ever. You have to either have more rushers than blockers or over load a side. Otherwise, you need to control the blitzer yourself and move him so that he is rushing in a gap and not just straight ahead. I have even had the dropping DL in a zone blitz get an INT.
There are many parts EA never explains. Use the same settings and trying playing D with a bunch of 90 rated speed guys at every position. It is amazing how many blitzes get in without any help. Yeah, obviously right. But the point is if you are blitzing with guys with average speed you are not going to have the same success if they were faster.
Try, subbing in your fastest LBs on plays you plan to blitz. On Nickel or Dime packages make sure your fastest LBs are in the game, not just the highest rated player.