Here's why Draven and Twitch are owning solo queue right now
Draven and Twitch are the kings of League of Legends' ADC meta right now, and ranked solo queue is their kingdom.
Both Twitch and Draven are very different types of marksmen, so it's odd that they'd both be running the show at the same time. Typically, any given meta favors one particular type of marksman, so ADCs of that type rise up.
For instance, when the tank meta came around, the tankbuster marksmen, like Vayne and Kog'Maw, became the flavors of the month. Oddly enough, Twitch is an attack speed hyper carry, Draven is an AD-stacking heavy hitter. Together, they hold the highest and second highest winrates in their role, according to League stats website OP.gg.
The League of who?
Draven, obviously. The axe throwing egomaniac has two things to thank for his climb to stardom. First came the buffs in Patch 7.1. Draven had been feeling particularly lackluster after the assassin class update two patches earlier, and he was being buffed to give him some early power in lane. His buff, which added a base damage to his spinning axes and changed the damage scaling from total AD to bonus AD, definitely helped him out, but it wouldn't have been enough on its own for Draven to take over.
There were changes made in Patch 7.9 that combined with his new Q for the perfect super-buff. The changes took several high AD items and raised their AD even higher to compensate for the increased armor that tanks would be getting. It just so happens that Draven builds one or two of those items early in every game, and that boost to AD stacks harder with his new Q, so it turned into an indirect double buff. What's more, Infinity Edge and Zeal were both made significantly cheaper, and those are his mid-game items, so Draven walked out the winner. He benefitted from the item changes in Patch 7.9 more than any other marksman in the game, and it's all because of the buff he received in Patch 7.1.
Historically, Draven has performed decently in solo queue but never in professional play. With the first week of the Summer Split beginning this week, don't be surprised if you see some Dravens hit the stage.
It'll only hurt til' you die.
Twitch's rise to stardom is less ambiguous than Draven's, and it can be pinpointed at one specific point in the Season Seven timeline—Patch 7.5. In this patch, Blade of the Ruined King (BotRK) was buffed hard, and since BotRK has been a part of Twitch's core items for years, this obviously had a significant impact on the sewer rat. The item gained a lot more AD and lifesteal at the cost of some attack apeed. Twitch had just become much more potent.
It wasn't long after that when Patch 7.9 brought its item changes, which affected Twitch as well. It affected him a bit less dramatically than Draven, but since Twitch was already hovering at the top of the meta, this gave him the bump he needed to start pubstomping lesser bot lanes. The bit that helped Twitch the most was the Infinity Edge and Zeal cost decreases. He typically builds critical strike items for his second and third items, so the lesser costs helped him hit late-game damage a little bit sooner. Since then, not many people have been able to contest Twitch's power, except maybe Draven. Twitch is already a popular professional pick, so expect that trend to continue—at least until Riot threatens some nerfs.