Why do tanks put Guard on healers in PvE?

Edit: Ugh. I never intended to start a flame war or anything; I just wanted to point out that a game mechanic was often not being used correctly. As it appears some have posted without reading the whole thread, here's my reply on page 3:
Since then, I've also come to realize (partly from this thread, and partly from tanking in SWTOR) that flashpoints are not quite like dungeons in that other MMO. I know that should be obvious, but many of us have seen that this game resembles WoW in so many ways that we assume flashpoints are the same too. I admit I'm as guilty of that as anyone else. In WoW, the tank is usually supposed to pick up everything and hold it in place while the dps burns them down. This was especially true in Wrath where nearly every pull was made for AoE. But SWTOR pulls aren't built that way: for one, the mobs tend to be more spread out, there are more of them, and tanks here seem to have fewer tools to grab aggro on multiple targets (my tank is nowhere near 50, so correct me if I'm wrong on this.) Second, there's a much greater spread of effective levels in each pull. WoW pulls are typically a few elites at or near the same level, but SWTOR pulls can have gold elites, silver elites, normals and weaks all mixed together, with the occasional mini-boss level thrown in. From what I've learned so far, not only is it very difficult for a tank to hold aggro on all that, they aren't supposed to. The tank grabs the silvers and elites while the dps takes out the little ones first, then goes after what the tank is holding. It sounds counter-intuitive to WoW players, but it works, and it actually makes healing easier since the tank isn't taking a huge hit up front.

It's about 8 months into the game, we've mostly settled in, and for most of you my post is probably old news. But if you've read this far, thank you for indulging a bitter old healer. I know tanking can be stressful; I've always thought tanking was harder than healing (tho' for some reason healers seem to get blamed more when things go south.) Anyway, original post follows:

-----------------------------------------------------------------------
It's pointless. First of all, it does not reduce the healer's threat. Yes, I know it says it reduces threat generated, but it does nothing to prevent uncontrolled enemies from going after the healer. If a healer has 100% threat on something, there is nothing to reduce. It goes like this: every enemy in a pull must be controlled, either by someone hitting it (preferably the tank) or crowd control. Anything that is not controlled is likely to go after the healer, and Guard will not prevent that. Besides, it only works on players within 15 yards, and healers are often outside that which also makes it useless for damage reduction. Trust me, Guard works far better on a melee dps that is likely to pull threat.

I'm not trying to slag off tanks here - I know it can be difficult with all the stuff you have to keep track of. I've been a tank myself. But it's really frustrating when tanks refuse to put Guard on anyone else no matter how I try to explain it. I even saw one ragequit after saying nothing more than "Guard works better on dps that pull threat." Another tried to tell me it was "healer aggro." Listen, there's only one thing you need to know about healer aggro in this game: it doesn't exist. It never did. Kindly remove that phrase from your vocabulary.

TL;DR: the only way for a tank to prevent uncontrolled enemies from swarming the healer is to hit them. Put Guard on the highest threat dps. Your healer will thank you for it.

We guard melee DPS - not healers. You are correct, adds will always go against healers if no one attacks them.

F.Y.I:
Guard:

• Reduces threat: No range limit (as long as someone else has plucked some threat - this will help, if not: it's as you say).
• Reduces damage taken: 5% at all times, no range limit.
• Shifts damage from target to tank - has a range limit.

Anyone to get a guard should be people wanted kept alive.. may be healers, may be DPS.. these things vary, but its a very nice buff I'd say ;-)

Actually there is a range, 15m. Try being guarded once, walk out of range and you will see an icon on your buffbar saying something like "Guard out of range"

As for the tank taking that 50% dmg, it works only in PvP

Well allright I'll give in on the taking damage, but threat and damage should not have the range limit of 15m... Else they've made grammar mistakes in the tooltip:

While active, the guarded player takes 5% less damage and generates 25% less threat. In addition, so long as you remain within 15 meters of the guarded player, 50% of all incoming damage from enemy players is transferred back to you. Requires Soresu Form.

Ofcourse.. Nobody said this is currently working as intended...

I think the issue with guard is how many people think of it as a "set and forget" sort of skill. It's WAY more useful if you are paying attention and switching it dependent on situation, IMO.

I'll guard a healer by default, then swap it over to a DPS if someone is consistently pulling aggro. Certain fights other DPS might pull more, or the healer may genuinely need it in the fight. On fights that trade aggro, I sometimes even put it on the other tank when I pull. Keeping an eye on what's going on gets me much more mileage from the skill.

I always pick the best melee dps to guard. I never lose threat to healers and I figure the melee will be close enough to benefit from guard.

However, if damage sharing is pvp only, and the other benefits of guard are not limited by range (as the tooltip suggests) then you should just guard the best dps, regardless of where they stand.

Can anyone confirm this logic and whether it is supported by how the mechanics of guard currently work?

Actually its completely up to the tank who they decide to guard. If dps is constantly pulling, then dps. If there is a lot of AoE going on in melee, then melee. If there are random AoEs being dropped everywhere, then the healer is best. If there are many mobs that spawn after a pull, healer again is best.

I run almost exclusively with guard on my healer. Why? Remember when you said that if you're healing and no one hits the mob? What about when I hit the mobbut it's still too far for me to Agro with my main skills AND taunt is down? This actually happens a lot, especially during speed runs. Sure I have all the main mobs on me but if dps is slacking and not picking up the little guys, that is going to kill you with spell knock back. With guard up, a simple hammer shot (no resource cost) will pluck the enemy off you. Without guard? Most likely 2-3 hammer shots, possibly an ion pulse, or maybe even a stockstrike / high impact bolt.

As a tank, I know the people who pull Agro the most and take the most damage in an encounter. It's not always the dps, it's almost always the healer.

Why? Because when dps attack, unless they AoE, they pull 0 Agro on additional mobs. Healers however constantly Agro ALL mobs. This is a major issue, specifically in situations with mass - spread out weak mobs.

That's why tanks put guard on healers. Dps just don't need it anymore.

If you mean FPs, I only guard healers if they comfortably outgear the dps, because undergeared dps aren't pulling anything off of me. Otherwise, yes, you're right, you always guard your strong melee since he's hopefully off killing the stragglers.

Alternatively, in OPs I always guard the healer no matter what, since they hit harder and because many pulls are a potential wipe if he drops as opposed one of your dps.

Then again, your thread is probably falling on deaf ears since the people who take time to read forums are probably already paying attention to how the game works best...

Here's my process for determining who I guard:
1. Is one of my group exceptionally squishy? Guard that guy regardless of role.
2. Does one of my DPS pull aggro at awkward times? Guard that guy
3. Guard melee DPS, because the 5% damage reduction probably helps them more than anyone else