4 and 5 cost champion availability/pool algorithm is bugged this patch

The availability is completely off this patch. It worked great up through patch 9.15, but something is wrong since 9.16. Every game there is at least one 4 or 5 cost unit that is completely absent from the game, even when half the lobby is building a comp that depends on that unit to show. It's not sitting on anyone's bench. It's not in anyone's lineup. It's most noticeable when it's kayle or swain, but I've seen it happen with gnar and several others as well.

Before this patch, if nobody was going for a particular unit, you were pretty much guaranteed to find it at least once with 30g worth of rerolls. After patch 9.16, it doesn't seem to matter what anyone else is going for - even if a unit is absent from the board, it's nowhere to be found. Meanwhile people are finding two-star draven/jinx at lvl 5/6, when a 2-star draven was virtually unheard of pre-7 before this patch. Something is wrong. I've played 50 games this patch hoping it was just some weird RNG, but there is something consistently wrong going on.

I'm D3 with 171 ranked games and then I have another 50 games on a gold smurf. Not a huge amount but enough that I feel like this is legit. I also haven't been dropping elo due to these changes, so this isn't a "I dropped rank, fix ur game" post.