How does the team matchup system works in Ranked solo Q ?

Hello,

I am PKR Redeeming, I play alot league but I still don't understand some parts of League of Legends system. One of them is the matchup we have during the queue. Sometimes I feel like I shouldn't be matched with some players. But other times I feel like i've been matched with the perfect team! Recently, i've been playing some really good games, my kills/deaths ratio was really good, and I won easily my lane. But later on the games, I found out that my partners were litteraly losing on everything. High amount of deaths, no teamwork, no grouping, spliting was poor and unefficiency and on top of that , they were giving alot of free kills. Fortunately, my games aren't all the same, as I said earlier, sometimes I have a really good team, but I feel like it isn't only about us having a good game or not, I feel like it's something else. My question is , are we playing with people having bad games when we have good ones? Something that could balance or help any others ''bad players''. I don't want to upset anybody that has bad plays or bad games, just want to figure out if there's a reason why my K/D ratio is approximately 4/1 and theirs is 1/3, 1/2. That's kind of frustrating considering I've been playing the whole game perfectly and still lose because of my entire team being dead most of the time.

Thanks.