User blog comment:Poisonshark/PS's "Mysteries of Laning Conventions"/@comment-1330314-20140808205213

So, before going into why certain roles go into certain lanes, opinion on your suggested picks:
 * Support is decent, a long with a few other high-CC mages such as  and . The only problem, though, is that mages are extremely dependent on leveling to remain relevant, which means that these guys won't be as effective past the first few levels, even if their level 1-3 is incredible. The other problem is that they're damage-focused rather than utility-focused, and with the lower income of a support and their slower leveling they'll tend to fall off pretty hard. It's a potentially effective pick, but a risky one, which is why "traditional" supports and actual utility mages are more viable bot lane.
 * Some marksmen like and  are a better fit for top than bot.  and  are less frequent, but still there occasionally. In general, ranged champions give most top laners a really hard time, but the issue is that you're either stuck with two marksmen on your team (not a good idea unless you really want to splitpush), forced to turn your top lane marksman into a bruiser, or forced to put a non-marksman in bot lane. If top lane's your marksman, the lack of a support will make them more vulnerable to ganks, and if top lane's your bruiser, you're better off picking an actual bruiser. Putting a non-marksman in bot lane means you'll have less control over objectives (namely, which you won't be able to kill as fast), and will eventually be unable to compete with the other marksman's pushing power. Once they level up a bit, melee top laners will be able to engage your marksman and overtake them, preventing them from farming as well as they should.
 * Putting a top laner in mid lane means your champion is at risk of getting poked to death: most mid laners, including melee champions, have some kind of long-ranged poke that they'd be able to abuse to force your top laner into their tower. It also means that the enemy mid laner, without having to engage you, will out-shove your lane and out-roam you, as their burst will be a lot more impactful on other lanes.

In general, lanes are organized for the following reasons:
 * Mid lane: Being the shortest lane in the map, it's the one where your laner is going to level up the fastest. Current laners (mages and assassins) are extremely level-dependent, so this is the best fit for them. When mobility was less common among mid laners, the short distance from lane to tower meant mid laners could more easily get out of reach of junglers. Mid lane is also the one where your champion gets to exert the most influence over the others (along with the jungler), by either pushing (getting the tower means unlocking the shortest route to the enemy nexus), sieging (defending the tower means the enemy can't push as hard) or roaming (tipping the other lanes in your favor means you can rush to the end of the laning phase and start pushing mid), which also creates a rock-paper-scissors dynamic (sieging counters pushing counters roaming counters sieging) in which you need a champion able to follow this paradigm in order to fit.
 * Bottom lane: As the lane closest to, aside from mid, you're going to want to have as much of your team focused around that objective as possible, as it's extremely important early to mid game. Marksmen start out weak, and so go best with supports, who are designed to function without having to last hit minions. Neither class is that dependent on leveling to gain an advantage, as marksmen are item-based.
 * Top lane: Because top lane is far from most of the early game action, you're better off putting champions who don't specialize in controlling objectives and who can stay strong even if they don't get too much jungler assistance (i.e. who don't scale well). Tanks and bruisers generally fit this, which is why they're top.