Against agi 4 teams you just have to force them to make as many rolls as possible. Mark everyone you can and try to force them to choose between dodging or making a 1d block. Also, you often need to worry less about the ball carrier and more about possible receivers. Any elf team is capable of moving the ball the entire length of the pitch in a single turn, it does you no good to have the ball carrier surrounded if he dodges out and passes to an open receiver who then runs farther down field, hands off the ball, and then THAT guy runs his full move for the TD. You also need to plan around skills like sidestep and fend. It may not be worth the risk to block someone with sidestep because you might push them out of coverage or at least make their dodge roll next turn much easier.
Honestly, I think the best thing you can do to learn how to play against an agi team is to actually play one yourself for awhile.