I think there needs to be an S+ and S-. Tyranitar answers so much of the tier and so is straightforward to implement and use that it deserves to be in its own rank.
It almost got 50% usage in the latest tour which is in a league of its own compared to the other S's who were all in the 30's.
If there's any reason why people are looking down on Lucario, that's because it's the most over prepared for mon in the game. I prepare for it more than anything else, just because it's one of the two most deadly sweepers in the game, and even then an Agility set can catch you out. Definitely A+ for sure. On the flipside, Gyarados is rarely prepared for and thus gets away with massacring so many teams (this crime is usually committed by people who didn't start off playing DPP). The DD LO set is powerful and it's good at drawing out the Rotom-A's and Zapdos, working hand-in-hand with Tyranitar. Another solid A+. I'd probably put Gyarados a little bit ahead of Lucario, just because Lucario has more stable answers that are relevant in the metagame.
Infernape is shining right now. Both Mix and CB sets are really effective. More people are catching onto how good Agility Empoleon is, and Infernape is one of the few mons who can actually threaten it with CB Mach Punch once it's got the Agility up. On the subject of Empoleon, I believe it should be A+. Like Gyarados, it's criminally under prepared for and ends up sweeping so many teams by itself. Even if it doesn't, it punches big holes in the mid-game, leaving something else to clean up.
Crobat is suffering with the increase in Zapdos leads, and I haven't seen a good team with it in ages. Drop. As for Zapdos, I'm split. It's not as metagame defining as the rest of the S tier, but I can't shake off the feeling that it's one of the big reasons why Tyranitar is so popular.
I'm not too keen on Dragonite. I used to like it as an attacking lead but I'm starting to lean towards SR-setting mons again. I also feel like it's sweeping set is not as good as Gyarados'.
What's the reason for Azelf to not be in A+? I always find it to be a lead that does its job well enough.
Weavile is kinda cool, he deserves to be in B.