User blog comment:Tayzer/My own league story: supports/@comment-5663427-20131228181445/@comment-24226573-20131228184827

Janna is a strong support to be honest. an AoE knockback/heal that becomes strong with a bit of AP, her Q AoE knockup can easily clear waves with a bit of AP (Morrelonomicon should suffice). Her passive boosts the Movement speed in a decent radius around her and in the current meta mobility seems key. And you're very, very,very wrong on her slow, this I copy/paste from her wiki page about Zephyr's slow: It's reasonable to say that she has over 100AP lategame, meaning that she'll have a 46%, 3 second slow, and it isn't a skillshot so once she's in range it's a hit. I take that over wonky Blitzcrank grabs anytime! and that's not even counting her ability to shield turrets with a strong AP scaling shield, and give this to allies as well, with an AD steroid to boot!
 * MAGIC DAMAGE:  60 / 115 / 170 / 225 / 280 (+ 50% AP)
 * SLOW:  24 / 28 / 32 / 36 / 40% (+ 6% per 100 AP)
 * " Janna launches the elemental to deal magic damage and slow an enemy's movement speed for 3 seconds (capped at 80% total). She loses the ability's passive benefits while it is on cooldown."

Leona always had been popular,and Thresh hasn't been nerfed. Yes his Q cooldown (only his Q, *dat nerf*) has  increased but with a little nudge: landing your Q reduces the cooldown by three seconds, flat. just that. bam, and at max level, the cooldown is exactly the same (12 seconds), now landing a Q means that the cooldown is actually lower than it was, they also shortned his AA windup and thus buffed his 'between skills' damage. They made Thresh less of a noob-tube pick, everbody forced to go support just went Thresh and it was all ok. Those who are now skilled with him will be rewarded for it.

Blitz is a one trick pony (and one of the aformentioned 'noob-tubes'), skilled teams -should- be able to dodge most of his skillshots, leaving him with little else to do, also QSS and/or Cleanse and/or Spellshield (Sivir, currently very strong).

Coming back to Leona. Her cooldowns haven't been lowered since V1.0.0.123, in V1.0.0.150  They just fixed the tooltip to correctly display the cooldown. So only her ultimate has gone down in Cooldown, that's not a huge buff now is it? Her changes to W means that she'll be less tanky early on, and when she's behind in items but will scale much better into the late game.

Please, do more research before incorrectly hating on champions,gameplay or lane roles.