I actually think it is harder or easier depending on the type of player you are and this is because of the introduction of role selection. This is not taking into account number of known teammates effecting your chance of winning.
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If you are the type of player that can play 2 roles very well, but you are not too good at the other roles, you probably are having an easier time climbing than the previous season.
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If you are the type of player that can play ALL the roles well, but you do not specialize in any role, you probably are having a harder time ranking up.
Prior the introduction of dynamic queue, pick order designated the roles of players in ranked games. Many players were not very good at all the roles, but those that were, could move up in rank because they could adequately play all the roles if needed.
Players that were only good in specific roles had a harder time moving up if they were given a role they were not used to playing. They were basically playing their "non-main."
The ability to pick the role one feels comfortable with, has given players that were only good at one or two roles the ability to "safely" go into ranked games and get one of their main roles.
This also means, that players that were more "balanced" in their level of play lost a bit of their advantage as a player. Their versatility and lack of specialization means they are probably at a disadvantage in most games. If they play against a mid main only or a top main only in a game that player is probably more familiar with the role than they are, and perhaps their champion (if they are a one trick pony).
So the balanced and more versatile players have a tougher matchup, which could lead to more losses.
So all those players that were top or mid mains only, that probably CANNOT support or jungle or play other roles at all, is not losing the games they would lose due to simply getting a role they play poorly.
My friends that could only play a couple roles really well are a bit higher on the ladder than my friend that could play all the roles well.
One of my friends who got to Diamond 5 last season actually expressed this too me recently. He is stuck in platinum and he thinks its because he was a pretty balanced player that could play ALL the roles well. Now he is trying to learn a couple roles in order to climb more effectively.