Great feedback from everyone.
I'll add my .02 for anyone who's interested.
Training herders as compared to molossers/bully breeds is completely different as previous posters have mentioned. The mechanics as to how the perspective breeds work is rooted in instinct. To get the most out of your molosser/bully breed you should know the following:
1) initial protection work should be rooted in prey/play. Making the game too serious too soon and forcing a dog into defense can limit their usefulness/ability to think clearly/be responsive during sport/protection work.
Not all mastiffs have a lot of prey to begin with. A very experienced trainer can work these dogs with "prey guarding" which is tech light defense techniques to initially start the prey building process.
2) Bull breeds typically thrive on the conflict. Pressure is not necessarily viewed by them as a penality. It's part of the challenge and they are more than happy to see it through, readily eating appropriate levels of physical contact and verbal vocalizations depending on their experience level. A herder (typically) will fight and enjoy it to some extent, but he sees the fight as just that, a fight where he might lose if the guy is too tough. Pressure is a negative to him because it gives the impression that he might NOT win and that’s why he is doing it to WIN.
The combat dog is the opposite. Yes he too wants to win (no one wants to lose), but the fight is what he really enjoys. He is not fighting because he wants to win, winning or losing doesn't occur to them until it happens. He is fighting because he wants to fight. The more fight the better. It’s not a penalty at all, it’s what they want (even if they don’t know it at first). As soon as they win they should want to fight again. Not, crap calmly with a full mouth and enjoy the win. And don’t mistake wanting to fight again with wanting to play again.
If you want your molosser to be interested in protection he must be challenged from day one! Not dominated or nursed!
This is where the skill of the decoy is paramount. Applying the appropriate amount of pressure and backing off at just the right time will encourage the dog to enjoy the game - and view it as just that. A game between themselves and the decoy. The decoy is his sparring partner - who makes him work to relieve stress by fighting with intensity. Stress relief is either securing the bite or causing the decoy to flee, or being told to out/release the decoy.
3) because they are combat/gripping dogs getting them to out can be difficult. Using physical force on a combat dog which serves as a negative correction is merely viewed as part of the fight - they will deal with the pain because it's what the "work" entails. Multiple prong snaps or taps on the nose which works on herders maaay not work on molossers. I highly recommend tug games with your dog at home early - teaching the out prior to starting combative pressure through protection work. Where his incentive to let go is greatly diminished. I found choking the dog off the grips is an easier method towards teaching the out - and then quickly offering them the bite again so they can associate outing with regripping - making the out itself - when asked the reward.