I can't wrap my head around this SAC entry...

Interceptor is perfectly good at low level, and since 5.5e lets you change your fighting style on level-up, you just replace it when it becomes obsolete. There's a decent argument that the problem isn't with great weapon fighting:

• Archery (+2 to hit) means your hit chance goes from 70% to 80% (+14%). It varies slightly with tier, as attack bonuses generally outpace AC.
• Defense (+1 to hit) in tier 1 is reasonably likely to reduce enemy hit chance from 40% (+5 vs AC 18) to 35%. That's the same 14% as archery.
• Dueling (+2 damage) in tier 1 is probably increasing 1d8+3 to 1d8+5 (+27%). It loses effect with level faster than archery, but remains relevant even in tier 4.
• Great weapon fighting (greatsword) is increasing your 2d6+3 (10) to (11) (+10%). As great weapons have more damage boosting options, it drops off a bit more than dueling. The 2014 version was about 50% stronger.
• Thrown weapon fighting is a clone of dueling.
• Two weapon fighting in tier 1 is probably increasing 2d6+3 to 2d6+6 (+30%). It scales with ability scores, but not with extra attack, so its scaling is worse than dueling.

The real outliers, then, are dueling and two weapon fighting.

Quote from Natrel >>

Quote from Agilemind >>

The short answer however, is that Fighting Styles are supposed to be roughly balanced with each other

 
Well then they did a shitty job at it because Interceptor and Protector are total garbage.

 I'm using Interceptor Fighting Style on my level 8 paladin character and I can assure you, it's far from garbage. The amount of damage it has soaked up in combat would have dropped some of my party members a few times. Sure enough, it doesn't really scale, but in early stages enemies hit you for 1dX+3, so Interceptor has a chance to fully negate the damage completely. When enemies start dealing 2dX+10+3dY damage three times per turn and/or when they have a +14 to hit then obviously Protection and Interception lose usefulness. It doesn't make them "total garbage". And there is always the Martial Versatility to change fighting style.

Quote from Pantagruel666 >>

Interceptor is perfectly good at low level, and since 5.5e lets you change your fighting style on level-up, you just replace it when it becomes obsolete. There's a decent argument that the problem isn't with great weapon fighting:

• Archery (+2 to hit) means your hit chance goes from 70% to 80% (+14%). It varies slightly with tier, as attack bonuses generally outpace AC.
• Defense (+1 to hit) in tier 1 is reasonably likely to reduce enemy hit chance from 40% (+5 vs AC 18) to 35%. That's the same 14% as archery.
• Dueling (+2 damage) in tier 1 is probably increasing 1d8+3 to 1d8+5 (+27%). It loses effect with level faster than archery, but remains relevant even in tier 4.
• Great weapon fighting (greatsword) is increasing your 2d6+3 (10) to (11) (+10%). As great weapons have more damage boosting options, it drops off a bit more than dueling. The 2014 version was about 50% stronger.
• Thrown weapon fighting is a clone of dueling.
• Two weapon fighting in tier 1 is probably increasing 2d6+3 to 2d6+6 (+30%). It scales with ability scores, but not with extra attack, so its scaling is worse than dueling.

The real outliers, then, are dueling and two weapon fighting.

 Interesting, I guess since the loss of the -5/+10 attacks the value of Archery has had a big decline in potency. Defence is arguably the worse fighting style as it scales really poorly since enemy attacks outstrip AC pretty quickly. Two-weapon fighting in general is kind of broken how powerful it is in tier 1 TBH, it is simply the best option for all melee characters before level 5, which is a shame. Dueling IMO should be the most powerful fighting style because sword + board has so little going for it in general. I kind of wish instead of making Thrown Weapon Fighting as separate FS they had just amended Dueling to include thrown attacks, because the stackability of Dueling + TWF is pretty broken. But again this all comes back to my previous point that DnD is just a really poorly balanced game. 

Quote from VerilyRaze >>

The difference between Savage Attacker and Great Weapon Mastery is that Savage Attacker specifically refers to the weapon's damage dice - the specific subset of damage attributed to the basic weapon category itself - while Great Weapon Mastery refers to the damage from the attack - which includes all of the extra dice of damage you might receive from various sources.

I'd say that, RAW, SAC got it wrong here. They should have either said "oops... that's not what we meant" and issued an errata or simply ruled on the actual text of the rules.

 I have to agree with this. The sage advice contradicts the text of the rules. Since the text on critical hits and savage attacker is mechanically distinct, GWM is phrased like critical hits.