While I agree with what you're saying, I do want to point out some holes in what you're saying.
Altec has always carried with the help of Pobelter. You're basing this off of what? Because they played on the same team that? Are you trying to say that Altec couldn't do well on another team unless he has solid players around him? Well that can be said of anyone in the LCS, it's how teams win. I'm not saying Altec is god or that he's even better than Louis, but you can't dismiss his achievements (yeah yeah, he hasn't really achieved anything big but the fact remains he is an LCS caliber ADC) so lightly.
You point to KDA as a main statistic but there are flaws with using that as a main metric. What about damage dealt? You're also looking at a small sample size; how about his earlier performances? Understood he has markedly improved (which suggests he has a lot to learn and can do it quickly), so there is a case to be made for both ADC's.
I'm not disagreeing with you in any way here. I'm just saying your arguments has some holes.
In my honest opinion, everyone of them deserves their spot in the LCS because they just beat an LCS team. I want to see how they do in the summer split. My expecation is this: I don't know if AlexIch is going to play with them next split (he's still just a sub, right?) but assuming he's not, Seraph is their carry player who they are leaning on as the main threat of the team. They funnel a lot of resources into him be it split push farm, jungle attention, etc. Now; we've seen Team 8 do this where they have their top player be the main carry and for the most part everyone else be a role player and they haven't exactly risen to the top of the standings. In my opinion, TDK will need to pick up an elite mid who can compete with Bjergsen, XWX, and even Fenix type players who are mechanical monsters. The team is too one dimensional when they expect bot and mid to simply play safe until later in game when they can team fight (albeit, very well). But, if I am updated, this is the case as Alex is a sub (maybe he should be a starter?). Who knows. If not Alex, maybe Pob (he's in a Link position; talented but hasn't lived up to lofty expectations that come with his mechanical prowess)? My guess is he's mulling his future and ends up deciding to go to school.