The ad caster role is very weak overall at the moment. MoM helped a bit, but there are still massive weaknesses in the class.
Lets look at the list of AD casters (sorry if I miss some):
Now half of these are strong and half a rather weak, and are very situational picks.
Of the half that are strong you can seperate them into two categories.
High base stats champions
Champions that are built differently to AD casters
Riven and Lee Sin have high base stats, strong ratios and strong base damage. This is why they can be built pure ad with little defence and still be effective. Although quite a few people build them as bruisers they are viable with an ad caster build.
Ezreal and Urgot can be build differently to AD caster standard, which is why they are still viable. Ezreal is built as a carry, picking up a sheen ofc (much like corki), and can be built AP. Urgot is a good ranged bruiser and a carry.
Those 4 are the effective half of the AD caster pool, however on the other side we have garen, renekton, pantheon and talon.
The problem with these 4 is they really need to built as AD caster.
With garen and renekton they get tanky enough with base stats and a single defensive item, which is how it should be. However they don't deal enough damage late game, whilst these two are very strong early game they become weaker and weaker late game. And a small amount of armor shuts them down.
Pantheon and Talon are very situational picks. Pantheon is effective against few other laners, (he is very good against gp top though). Talon is good against a few AP casters, however that can end up screwing your comp over with too much physical damage. Both of these champions fall off late game with just a bit of armor, unless they get ridiculously far ahead.
The class of champions really just needs new items for late game, which would solve the problems of the weaker sides (i.e. their terribad late games) and a small buff to base stats for talon and pantheon.
These changes would make some sit picks/weaker champs stronger, and open up more builds for the strong champs currently in the class. There really needs to be a better build up from brutaliser. Maybe it could combine with bilgewater cutless to give an item with AD, armor pen, lifesteal and some spellvamp.
TL;DR Ad casters need more items to open up their builds, and yes its this thread again.