I think the MMR system is bugged in some way

I have been playing this game for a very long time and I understand how the league system works and the mmr behind it. I understand LP gains and loses are based on how far away your rank (league) is from your real rank (mmr). Recently I have seen 4 accounts that break the rules of how this is all supposed to work and I see no explanation for it and even if there is one it is logically flawed. I didn't save the opgg of the first 2 I saw but I just played with 2 in the same day so I can link these.

http://na.op.gg/summoner/userName=xxxkbi http://na.op.gg/summoner/userName=suckmebigboy

These two players have ranks far above the games they are getting matched in and after talking to both of them they both say they get very high LP gains and low losses. Both are D1/Masters and playing in DIAMOND FOUR games. That disparity is huge. Either they are really d1/masters players and they should be playing against D1/Masters players OR they are low diamond players some how abusing or benefiting from a bug giving them incorrect LP gains. The MMR of their games seems to not change much despite wins or losses.

I don't know what is causing this but every account I have seen with this phenomenon has been a fresh lvl 30 this season. Normally fresh accounts should have mmr higher than their league rank and will skip divisions to catch up but it still isn't enough. Usually smurfs end up plat 5 or plat 3 in diamond 5 games and then d5 in d1 games not the other way around.

Let me know if anybody knows anything about this. Is it an exploit? Is it a bug? How does it happen? Does it have any effects on the larger player base outside of these specific examples?