In games that are mostly about team playing against other human opponents on equal footing average player will have 50/50 win to loss ration. However matchmaking system might manipulate when a player experiences wins and losses by matching him with weaker teammates against stronger opponents.

My question is, do these games use psychology to know when you should experience win and when loss to spend more time with the game and do the skew win/loss probability for optimal player engagements?

Are there any white papers on when is a right time to administer loss to keep player motivated rather than discouraged?