Smurfing has been an issue for players in lower brackets of League of Legends ranked play but it appears the developers found a way to deal with it.
League of Legends is a rather stressful game due to the high octane combat, the need for focus on both mechanics and macro play, which can wear players out, especially in the upper echelons of the ranked ladder. This is just one of the reasons why highly skilled players will make a new account and start over as they find wrecking the less skilled players a relaxing activity.
What they often forget is that the stress doesn't magically disappear - it's just transferred to those on the receiving end since one team gains an unfair advantage with an unusually skilful player on their squad.
Due to the nature of League of Legends ranked ladder, it takes quite a bit of time to swim out of lower ranks such as Bronze, Silver or Gold so these smurf accounts tend to stay awhile and ruin more too many matches before collecting enough LP to go through promos and to higher tiers.
Riot Games apparently came up with a way to counter this issue as players started noticing that smurfs are getting matched against each other more often than before. Furthermore, Silver players started matching with Platinum ones instead of with other Silvers.
At first, the community wasn't sure whether this was an intentional change or just spaghetti code but Mark Yetter confirmed the former to be the case on his Twitter.
This sounds great on paper because the actual Silver players will get opponents with equal skill level but it remains to be seen whether the system will work and how much adjusting Riot will need to do.
For example, if a player is in Silver but is consistently matching with Platinums, they should definitely gain more LP than we are used to seeing and possibly skip promo matches more often.