Originally Posted by
absynthe7
Lots of things can affect healing in a single raid encounter - but if his overhealing is greater than your actual healing, then it sounds like you're much worse at healing than he is. Maybe not as bad as it might look - if you had a ton of overhealing, he could have been healing people before you could get spells off, which only means he can react a split-second before you and there isn't that much damage to heal. If your overhealing is low and your actual healing is low, it seems like you may be a bit... underskilled and/or undergeared.
Which is fine! You just made 85. Read up on your spec to make sure you're using your most effective heals (particularly for large groups - I know that Shaman healing is very different in 5-mans and raids), learn and use your cooldowns (there's not much reason to before raiding, so you might not be used to using them effectively), get some practice in the 5-mans. Make sure you've got food and flasks for raids. Try some random Battlegrounds so you can get used to pressure situations and group healing. Don't let one nay-sayer get you down - with some more reps you'll be more than capable of holding your own.