Taric's Heal

What is going on with Taric's heal? Why is it not healing the correct amount ever? When I'm healing my self i will usually heal me for about 40 HP under what I'm suppose to be healed for. When I heal other it will just randomly heal us for a wide range of amounts. Like I've had the level 5 heal heal my ally for only 120 health and heal me for 300 when I'm only suppose to be healed for about 260 health. I've had the heal heal at level 5 for 150ish health and heal the ally for 200. Why is this like this? Is this intentional to handicap Taric users? Personally I'm a big fan of using Taric and I tried to figure out if the wording was wrong or something on the tool tip and checked the wiki to see if the healing is suppose to be split between you and the ally, but first that wouldn't make sense because that is an rng heal and second because that still doesn't explain the incorrect healing amount for healing himself.

Could you do something about this because this is a huge handicap for Taric players like myself?