The pool change was a reduction in copies. For any given champion...
T1 can have a max of 3 3-stars, down from 4.
T2 can have 2 (2)
T3 can have 1 (2)
T4 can have 1 (1)
T5 can have 0 (0).
So the only way to really get those 3-stars is to burn win/lose-streak gold on re-rolls. Of course, you're not going to do that on a lose streak because it defeats the point.
My biggest complaint this set isn't the early 3-stars. They were a thing before (even more common in set one from my experience), and mid/late game the overall comp is more important (Especially if running light). My bigger problem is how the reduced pool made it noticeably harder to make any comp at all. Early econ is almost suicide because all the synergies get vacuumed up before you actually start rolling anything. Loss econ is even worse.
I've been trying to make early econ work, but it's a coin-flip if whether or not I'll have more than 1 2-stars before I get knocked out at bottom 3 (not even taking synergies into account). And the fact that I'm not rushing a synergy early on generally means the pools are near empty before I can actually buy into them.
Riot's effort to make everyone build unique comps has just resulted in only the top 4 ever having a reasonable chance at a viable one.
Malzahar and Thresh are probably 2 of the strongest characters relative to their level (Personal opinion).
I've managed to build comps entirely around malz.
I'm increasingly running double Thresh just for the shield stacking (2 2-stars is actually more valuable than 1 3-star if I can pull it off).
