Bullard won't start.
They will save him for sub packages and passing downs.
Let Ego/Unrien suck up double teams and play the run. Keep Bullard as fresh as possible for obvious passing downs.
That makes logical sense ("save him" for obvious passing downs). But there's also logical reasons to start him.
First of all, just because he's likely the best passrushing DE, doesn't mean he isn't also likely one of our two best run-game DEs. Bullard had more Tackles and Tackles For Loss than both Ego & Unrien (Sr Yr & Career), and he's by no means a small 3-4 DE at 6'2" 290lbs.
For the sack of argument, let's just say he's as good as Ego & Unrien against the run, & the best passrusher.
1. More 3-&-outs wins more games, & keeps every D player fresh, including Bullard. Best player = more 3-&-outs.
2. These days, we see a lot more passing on 1st and 2nd down.
3. He's a rookie who needs game experience anyway. Give it to him and see how it does in run & pass.
4. To a lesser degree... substitutions during the game aren't always an easy option (hurry-ups), and can negatively impact player's awareness of the game situation and his feel for the game.
If Bullard is the second best DE, I would start him. If the Defense can't get off the field, or Bullard isn't staying very fresh, it's a given we are going to rotate players, but that's not a reason not to start him and give the team it's best chance at 3-&-outs.
I think Fangio will do what he says he does -- he'll throw everything at Bullard and see how he handles it. If he can progress with both run D & pass, start him.