Is that about Dominion?
I don't know; some times it's the most fun I've had playing competitive videogames, and at others it's just... ugh.
I guess the problem I see (I might be imagining things, as I've not played LoL in general that much) is that AD melee carries snowball extremely fast, while AP carries are generally less useful as a whole. I mean, every Xin'Zhao I've played has been a roaring success ending with me at top, and AP Twisted Fate, Annie and what have you I've failed miserably.
I guess it's more up to the kit the particular char has, since last night a Ryze DEMOLISHED us, and I've seen Veigar used well, but the facts are - if I jump on someone with Xin and 5 or more minutes have passed, he's going down, and the other way round - if an Akali or Talon jumps me it's 20 secs of browsing items again.
I guess my question is, is this a real problem, or do I need to get better at vidjageims?
Dominion is really about picking your fights wisely. You can't simply fight 3 people and take a turret. Likewise, if 1 person comes to try to take your turret with 3 of you there, it's not happening. What that means is if someone is just walking around near you, then you have to choose whether you're going to chase him or not. You have to choose between taking a turret or killing someone. You also need to know when to attack and when to defend.
So, if you're getting repeatedly killed by a certain champ, you should stop fighting them alone.
Team comps should include something like: Initiator, Carry(x2), Assassin, and one unknown.
The Initiator is a fast, tanky player that can start fights at turrets for the carries. They are not a tank, per say, as they won't be taking damage for players, but are sacrificing themselves for turret damage. They should also be defending turrets, even against 2 or 3 people (if Garrison is up, they can win 1v1 and 1v2, and stall 1v3 for a few seconds, if another player is on the way). If there is no carry to fight with and no nearby attackers, they should be taking undefended turrets. Garen, Singed, Rammus, and probably Galio are really good at this. They'll almost always want Ghost and Garrison. Garrison is ridiculous if used correctly.
The Carries are obvious, but they should have some form of long range. Gangplank, Ezrael, Ashe, and Twisted Fate would be good choices. The long range skill is for defending turrets that you cannot reach in time. They should take undefended turrets if possible, but also pushing minions to the turret is nice for them, especially if they are defended by one (maybe two) players. They can defend, but only if there is no other option. 1v1, they should kill most players, but that's more of the Assassin's job. They will want one of Promote/Garrison (either for pushing or the attacking and defending of turrets) and either Ghost/Flash for defense. Ghost is usually better, since it has a lot more offensive capabilities, too.
The Assassin is a stealthy (or just fast [or possibly just outrageously strong]) player that can eliminate people 1v1 but rarely fights at turrets except as ganks or pushing with another player. They can hunt down players or defend, but they must also take undefended turrets. Akali, Talon, Irelia, and Master Yi are good examples. They will not need either Promote or Garrison. They should take 2 of Exhaust/Ignite/Ghost, depending on how well they can escape or their personal preference. If they lose a 1v1 fight, then it better be against the enemy team's Assassin with help or incredible luck.
I haven't decided what the fifth person's job is. It might just be one of any of the three, though more than likely a third Carry or someone with an annoying CC(s). They might have a combined job of Carry with CC (but no long range). There job might just be Harasser.