first the game doesn't sim at all based on your subs , even if you set your subs for every scenario.
It sims based on the depth chart. There may be an option in your coaching profile to make sure it is set to 3-4 but the game may still sim on 4-3 all the time.
the best solution to overcome this may be to Create another Farrior(same ratings etc..)and create him at Outside Linebacker(be sure to put him at the same side as Haggans right or left ?) and delete/cut the original FarriorMLB
- In your human played games you could play him at his real position of Middle linebacker by using the subs ,and when you had to sim at least he would be your 3rd linebacker and Haggans wouldn't start. It still kind of sucks that U would have 2 defensive tackles and 3 linebackers but at least Farrior isn't wasted.
Also if you don't plan to sim many games you could just alternate Bell and Farrior ...