As it so happens, I didn't think standing back and spamming Shield Lob would get me aggro back. I did, however, believe that a Provoke + Shield Lob would do the trick. Which is exactly what I did. It failed anyway, which is what I didn't expect, though I know what caused it. By the time that had happened, it was too late to do anything else. The funny thing about close-range combos is that they're a lot easier to land when your target isn't being led on a merry run away from you.
EDIT: By the way, if you think I was only complaining about this one run in my original post, you are sorely mistaken. My grievances were built up, run after run, thanks to mistakes which I will freely admit not only I made, but other people made, yet which were all solely attributed to the fault of me and my co-tanks. Things like DPS refusing to stack for mechanics, or dying to a tankbuster I'd faced away from the group, because the DPS in question ran into it. And another run in which the MT died, and the WHM got aggro, then promptly proceeded to run in circles while screaming at me to pick up aggro when they had regen up on everyone, while I was also being hampered by paralysis that nobody deigned to cleanse.