I'm a rogue, never really raided with a caster and while levelling my warlock to eventually top the meters during raids, a strange thought came and I couldn't stop wondering ever since.
Is being close or far from the boss of any importance? Our incinerates and chaos bolts aren't instant blasts, and because of that they have to fly to the boss and this is where the real question comes - is being close or far from the boss affecting our dps? This might sound really stupid, but if we are closer to the boss, don't we damage him quicker and thus getting higher DPS, or my idea of how the dps meters work for casters is totally wrong? Even if we stand far away from the boss, the amount of damage from chaos bolts and incinerates will be the same as if we were right at the boss' back, but still...
Standing closer won't increase your dps unless you have something like immolation aura. If your spells have a 1.5 sec cast, each hit will land 1.5 secs apart. Be you standing 5 yards or 50 yards from the boss. The first spell might hit slower and the last one may not even hit but... that's such a tiny amount of spells. It won't make a difference.
Considering you still cast the same amount of spells whether you are 40 or 5 yards away, it won't affect. The only scenario it does affect is when you have to kill low health mobs(like Spoils of Pandaria) where your Incinerate won't reach the target before it dies.
This does actually come into affect on a few select bosses. An example of this being Rag in Firelands. Because of where the spells connect to him (his upper back area) it actually took travel spells a noticeable amount of time to go off in the combat log. There is however a maximum amount of time for this to occur before the server just counts the spell as connected. This is mostly implemented to combat lag but it works in a few other situations as well.