Problems with Tank threat in BC

[Eclipsed]

Just looking for some advice to give our raid tanks. I have hung up my shield and not tanking myself anymore. Currently I am playing a bard. We are experiencing a major issue with our tanks in Coil where our DPS are constantly threat capped. We can only do about 180 dps with relic +1 pld's before we encounter major threat issues on all bosses. ADS is even worse in turn 2.

I have verified they are acc capped (they are way over). They have some af2/allagan. They say they are spamming their threat combo as much as possible. We are not burning CD's at the start, and are giving them a good 10 count before engaging as dps. However in about 20 seconds after we start, we hit threat capped and it can take up to a minute of auto attacking before we can engage again. I used to tank, and never had this issue anywhere. So I don't really have any good advice to give. Do they just suck? Is there something they or we as dps are missing? Has anyone else encountered this? How are tanks holding threat on these dps that are supposedly doing 300+ dps?