It really depends on how they are under performing.

The clueless healer:
Generally they either need to find their clue or removed from the raid. Unless they are a real life friend of either the guild leadership or raid leadership then you can gradually de-prioritise their position within the raid. If they are a nice person, hopefully they'll find their clue before being completely removed and get back into the main stream.

The distracted healer:
They need to be told in no uncertain terms that they need to switch on. If they insist on watching tv or porn while raiding, you have little choice but to try and replace them if they don't improve.

Blow my mana now:
You have to get them thinking rotations and longevity. Normally if you can coach them they will turn out ok.

The nub healer:
Get your resident healing theory crafter to spend some time with them working through gear, rotations, regen, healing roles. If they have good potential refer them to EJ or a less technical reference site and give them the feed back they need (keep it positive).

The under geared:
Get them to spend their own time gearing and re-roster them when they have gotten to a minumum point you have set.

The under prepared:
Read them the riot act, there is no excuse for attending a raid without consumables or awareness of the content you are about to do.

Remember different people react differently, you need to tailor your approach for each individual.

Be careful of coming across too soft. Particularly never pretend to not know that the person is doing something wrong. If you have to take a firm stance later and need to lay down the facts, regardless of your intent of trying not to be bossy or whatever, you'll just appear dishonest.

If you know they're underperforming and you know you have valid suggestions for improving their performance, don't go out of your way to hide the fact that you know what you're talking about, because you'll just eat away your own credibility.

I am occasionally surprised at people's interpretations of my assignments, so re-communicating expectations can be beneficial. I'm not suggesting you teach people, if they are raiding healers they know but it never hurts to make sure you are both on the same page. One thing I've noticed, sometimes healers unconsciously develop a habit of not trusting the other raid healers and try to do everyone's job instead of focussing on their assignment. Or similarly, feel they have to heal NO MATTER WHAT because its all on them and put themselves in harm's way to accomplish this (Archimonde comes to mind). WWS data on who healed whom is good indicator if this might be an issue.

Whether your approach is a gentle reminder or a virtual slap upside the head, getting someone to trust you and the others can improve performance.

While I agree that you shouldn't be too..well..fluffy, the avoidance of being considered too bossy is only a side effect (which I do consider positive) of that particular way of talking to them - if you approach whatever your goal with the person is in a dialogue they will, I think, have it easier to pick up what you told them as they should then have an easier time understanding the trains of thought behind it. Even better if you can manage to make them think they came up with it all by themself.

There is certainly a time for despotism, but I view it as a last resort for dealing with problematic people - keeping your credibility while still being likable isn't all that difficult. Of course, you can disregard that and be blunt if the healer in question isn't overly sensitive when receiving critique, but I find that rare in this game in general.

If this is a well-deserved admonishment then certainly. Sometimes the cause of the problem is more complex than that though, and increasing healing throughput is a good way to solve it, and that is something you should be able and willing to judge.

An example would be the eagle phase of Zul'jin. Quite often people will focus too much on avoiding the whirlwinds instead of doing real dps/healing, and that makes the phase extremely painful as your dps stop trying as hard, shifting into survival mode because they're all at half health and don't want to get gibbed by the next whirlwind. But if healers simply spam their hearts out for a while then everyone is able to perform at near-max capacity and the phase is defeated quite quickly.

So, certainly stick up for the healers if they are being criticized unfairly, but also don't discount the power of brute force.

Currently I am the healing leader of my guild and I came to ask a little advice. It seems that our healers are getting burnt out on healing at an ALARMING rate and was curious if anyone had ideas to maybe, "keep it interesting". I have a hard time understanding why people get burnt out for the simple fact of I love healing...

Choose 1 healer a week to play an offspec on farm content and rotate who it is each week? Other then that, if your healers don't enjoy healing there is no amount of motivation that will change that short of straight up bribery. Healing is the most thankless and selfless task in the raid along with tanking.

I'll make a football (American football, sorry) analogy: your healers are your offensive line. Some people really like knocking a defensive lineman flat on his back. Others like being on the team, but given the choice would really rather be the quarterback (the MT) or a back/receiver (the DPS). The offensive line isn't exactly glamorous; how many kids do you know that have a poster of their favorite team's left tackle on their wall? And, like raid healing, no one really notices the offensive line until they screw up and the quarterback gets sacked (the tank dies).

I happen to like this analogy, although people look at me funny when I start explaining it.

One thing that is extremely important, and our biggest problem when I took over raid leading about 6 months ago, is communication. You need communication from healer to healer, tanks to healers, and healers to tanks. Just this past week we wiped on mother out of nowhere simply because we got a bit lazy and 3 of the MT healers were part of their own fatal attraction. No one paid attention to the raid warnings or spoke up that they were ported and simply no heals went out, leading to tank death.

Stress to your healers that if they are for whatever reason unable to heal the tank that they communicate that to their assigned targets so that other healers can cover or they can lean on cooldowns until that healer is back in action. When you wipe use your mod of choice (I suggest recount coupled with GrimReaper) to debug the situation then question your healers about what it looked like from their end. More often than not they will be more receptive and honest about what happened. If you jump down their throats immediately it will put them on the defensive and likely throw them off of their game a bit (different players respond differently but it's something to keep in mind).

After a little while you will get a good feel for each fight and how the raid healing should go, and it will be easy to tell who is slacking or where weak points are in certain assignments and you can adjust accordingly. You will also find that some people are just really good at certain aspects of certain fights (the different types of healers, as mentioned above), and you can utilize that to your advantage.

I recommend getting GrimReaper. It's great tool when figuring out if a tank died because of no heals or did he just get smacked too hard. It's available on wowaceupdater atleast.

Here are my tips of being the healing leader:

Organizing assignments

1) Pen and paper are your friend

It never hurts to write down your healing assignments so you can refer to them later. This is for a couple of reasons: if someone misses their assignment you can refer to it later. It's also a reference tool - the next time you do a particular fight, you'll know which healers you assigned to do, and which roles you assigned classes. After a while you'll start remembering more and more of the assignments in your head, and you'll have to refer to your notes less often.

2) Assign roles early

There is nothing that the rest of the raid hates more than having to wait for the healing assignments to be done when everyone else is ready to go. I usually hand out on the assignments while we're clearing the trash before a boss, then do a quick "everyone know what their role is?" before the pull. Any specific questions can be resolved well in advance of the boss fight.

3) Type out assignments

Most guilds have a healer channel all healers are expected to be in. If your guild doesn't, create one. Typing out assignments means that there is a record of what the assignment was - if someone wasn't there at exact moment they were handed out, they can scroll up to check the assignments. There is a record that is a slightly more permanent than a vent conversation.

My personal preference is not to use macros. My theory is that macros are easy to ignore, and if people know they can ask you to "spam the macro again" they're more likely to pay less attention when you hand out the assignments the first time. I take the time to type out the assignments in as much detail as i think is needed, and in return I expect the healers to pay attention to those assignments so I don't have to repeat them endlessly. I usually give a heads up like "healing assignments incoming" to prompt the healers pay attention to the heal channel for the next couple of minutes.

Evaluating players

Meters like WWS and Recount are an invaluable tool for evaluating performance, but analyzing them does require a degree of care when it comes to healers. There is a wealth of information, and raw healing numbers by themselves are often the least informative statistic. Healing numbers are affected by class (shamans will usually outheal everyone else except CoH priests on some fights), the role a particular healer is asked to play, gear, who they are grouped with (eg shadow priests) and a bunch of other factors. So what are you looking for?

Are there healing numbers significantly different from members of their own class? If there are players who consistently score lower than other players of the same class with similar assignments, further investigation is required. Is it gear, bad spell choice, inadequate consumables, laziness or what?

What spells do your healers use? For example, priests with consistently high Flash Heal usage might be a cause for concern.

Where are they getting their mana from? The buffs and debuffs section of WWS can a gold mine of information. You can also check through individual combat logs for thorough micro-analysis.

I recommend a combination of both in-game tools (like Recount) for on the spot analysis, and WWS for in-depth analysis after the fact.

There are also things to look for in-game. Are they keeping their tank alive? Are they keeping themselves alive? These are the two most crucial factors for a healer. Do they pay attention and ask intelligent questions? Do they cross-heal strategically and effectively (in some fights its a good thing, in others it isn't). Are they dispelling quickly?

Evaluating strategy

One of the hardest thing to do on a new boss I think is to determine whether your healing strategy is flawed and needs to be changed, or whether its merely execution issues causing you problems. You have to find a balance between giving a strategy enough time to prove itself a success or failure, and not rigidly sticking to a strat that's failing when changing things around might generate a better result.

If you love researching fights and devising strategies, you probably have the right mindset to be a healing leader. Frequently the job is mundane. The rewards come when you figure out to keep everyone alive on Brutallus with 7 healers, or M'uru with just 6.

As far as burn-out goes, my suggestion would be to over-recruit a little so that you can give healers time off. Even if you love healing, doing it night after night for months on end can wear you down. Especially since healers generally have to pay full attention for the entire night (including all the repetitive trash pulls). Giving people part of the night off or even full nights off can give them a chance to recharge the batteries for when you really need them.