Since June 20, 2019 MMR and skill points/rank points are the same thing.
Your Rank (League Tier and Division) is now determined by your MMR directly and adjusted by penalties, such as Leaver Penalty. As a result, you will see a bit more volatility in your Rank Points changes after winning or losing a game.
Further explained in the update from August 2019
With the changes introduced this season, rank is always updated by taking the change in rating and determining the equivalent number of rank points to reward. This leaves very few ways rating and rank can diverge and results in most players being shown a number equivalent to their rating.