although its not all the time it does happen when people Disconnect and don't come back for the ranked game iv'e had many games like it. happens to me and im pretty sure some if not most of u has had it happen. u can play on and try to win a game that's 4vs5 so unless a lane gets fed or your a better team fight selection there's not much you can do
It happens in normals too. Most of the time it's just that persons connection. Not much you can expect RIOT to do about it though
Unfortunately there is nothing you can do about a teammate dc'ing and you're right it's a miserable experience. In truth it's a miserable experience for both teams.
However, the system does arguably work itself out in the end. I know for you it seems that an afk happens on your team more often than the other way around, but in reality if people are as bad as many people believe that they are at this game (read: everybody's own personal god complex), then that means that naturally the enemy team will have an afk just as many times as you'll have an afk, so in the end it won't actually STOP you completely from climbing, will just be a minor setback.
My advice is if you find yourself on a 4v5 situation, just try to learn something new. Try to get tons of farm, or chain together abilities in your champs kit that you've never even known existed. What's more is while this is ranked, try to have FUN with it. This is still a GAME that you're playing and yeah sure it's not as much fun when you lose, at least you won't be as stressed out when you do indeed lose.
Trust me, as a person with some compassion that plays this game, I honestly feel terrible for teams that i'm playing against that have lost a person. I usually try to be polite and apologize on their behalf, or if the enemy team is cool enough about it (though still not generally in ranked) I try to convince my team to surprise surrender before their's can because it's just a cool thing to do :)
tl;dr: Just hang in there dude, I know it seems to happen more often to you, but that's just your brain using selective memory on you.
