I don't believe so, however there is a reason it seems this way. Or my best guess at least.
Leagues matchmaking system DOES try to force you into a 50% winrate as best as it can.
You ever notice every time you go on a long winning streak, your games get far more difficult? Often times a winstreak or rapid climbing is quickly followed by a loss streak as well.
This isn't just because you're climbing to higher levels, but also because the matchmaking system starts intentionally putting you in matches you are highly likely to lose, in an attempt to push you back towards a 50% winrate.
This is why you see games where the entire enemy team is several ranks higher than your team at times.
If you're climbing, and reaching your series, you're probably winning far more than losing, at least in the short term. This results in the system giving you your unwinnable games, and often enough that happens during your series.
Best you can hope for is to get lucky and winstreak through your series, then have matchmaking wreck you afterwards so you just stay at 0 and don't drop.