Ok so I have only played the game for an hour, and went straight into practice mode to try to find some blitzes. The best concept I have found is to blitz a guy over the guard and the tackle on one side, then one more guy outside the tackle. This is a 3-man blitz and the C, G, T on the other side do not recover. This is slide protectable, but heres a way to do it where its not.
4-6 normal (speed package) any play
1) shift line left, then spread the line after the LOS DT gets in his final position
-what this does is put the LOS DT directly over the guard. If you just spread the line initially, the LOS DT wont get far enough out, and when you try to bring the blitz from the left edge, the center will pick up the LOS DT and this blitz will not work.
2) Reblitz the DT and DE on whatever side you are bringing the pressure, put the opposite DE and DT in whatever zone you prefer.
3) Put both Middle Linebackers on the outside of each DE
-This makes the blitz look identical, and therefore unslideprotectable because the offense doesnt know what side the blitz is coming
4)Blitz the middle linebacker on the side that you reblitzed the DE and DT, put the other middle linebacker on the nonblitzing side in whatever zone you want.
-The blitz should get in from either side, without the center, weakside guard, or weakside tackle recovering. Shifting the line left and letting the LOS DT get in position, then spreading the line IS THE KEY. I believe if you put the middle linebackers on the inside hip on the DE's instead of the outisde hip, this will also work, so its personal preference.
Hope this helps