Most of my tanks are lean on attacks. I generally put a Nucleolus Exposure (acc/dmg HO) in Brawl. The lone exception is my invuln, who has 2 pieces of Pounding Slugfest for the +regen bonus (he already had 5 of every higher ranked regen bonus).
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You can also slot Kin Combat's chance for KD on Brawl to keep up with the theme. 
My Shield/Axe Tanker uses the knockdowns from the Axe attacks as mitigation. So far I only have 3 Axe attacks, and I do not yet have a continuous chain. Furthermore, the knockdown is not 100% reliable.
If I chain all 3 attacks, I am likelier to get a knockdown to occur, but all three could knockdown -- and knockdown that occurs while an enemy is down is wasted. He stands right up after the chain ends.
If I pause between attacks I am actually better able to keep him knocked down consistently, because IF an attack KDs, I can wait and try to KD him again when he stands. If it does NOT, I can immediately spam another attack to see if that one gets him down.
Clearly this is not competitve DPS I'm talking about, and maybe improved slotting and stronger defenses will render it moot --I'm 23 at the moment.
But sometimes I Brawl in between Axe attacks while waiting for the enemy to get back on his feet. Brawl does terrible damage -- but it doesn't force redraw, unlike Kick or Boxing. In theory, if it was slotted up a bit, I'd be gettig better mileage out of using it between KD-type attacks.
I realize this is speculative, just trying to think outside the box(ing) a bit.
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