Maybe I can help, because there is misconception from a healer standpoint about STR build and warrior.
You have to remember that VIT only equals more HP, and STR in the hands of a good warrior is beneficial to party damage and their self-healing. I only run all STR as warrior as once HP and accuracy thresholds are met, the rest of the stats should go into STR. Skills like Inner beast cooldown and Equilibrium (Self-heal skill) scale to STR, combine with berserk and internal release combos we can crit and i've healed myself for over 9k.
I doubt the warrior wasn't in Defiance at-all though, they were probably stance dancing. You have to be in Defiance and Provoke to get 0.5 off the MT since it copies the other's HP and aggro table. Going from Defiance to Deliverance shaves off -25% HP so that is probably part of what you saw. It may not have been damage being taken, just the Defiance max HP buff going on/off by dancing. Now they still have access to good cooldowns like Vengenece, if they don't needlessly burn them trying to get more Abandon stacks. It really comes down to warrior game play, and how much they can trust healers. STR alone isn't the issue.