So two things. Firstly, let's be honest, your screenshots aren't even showing off an impressive disparity.(Look at my match history losses for some fun ones.
Secondly, matchmaking is pretty much impossible to actually balance until you get to the higher tiers...where there aren't enough players to actually make it work effectively. Here is why:
Let's say you have 2 similarly skilled players by every metrics except one mains
and the other mains
. Riven crushed this matchup easy so it looks like riot matchmaking is bad. When you have 10 different players and 140 champions with unique abilities and interactions it just gets insane to actually balance.
On the flip side sometimes their matchmaking(particularly in series) is handing one team a free win.(https://matchhistory.na.leagueoflegends.com/en/#match-details/NA1/3062674788/38386924?tab=overview is a great example where we have an Orianna smurf on our team and they have a 43% winrate Voli on a series on their team)
So honestly, 80% of games are actually pretty well matched, though because of all the moving pieces it often doesn't look that way.
Cheers![slayer-pantheon-thumbs]