I understand that having struggling teammates will make the game harder to win, but I don't see how having a struggling teammate(s) make the game suddenly hard to the point of having any chance to win, if you are performing well. You can provide the extra help needed to get your struggling teammates back on track.
I do know that some games, it is quite seemingly impossible to come back from when the enemy team is far too ahead and everyone on your team is either equally weak or when one or two of the enemy are too strong. Games like that do happen.
If you have dependable friends to play with that are around your skill level, you can try to rank together for that extra communication and synergy.
Good luck in your Climb!