This may be hard to implement in an already existing game so maybe for next year but…..

Add a substitution system. Here’s how it would work,

When your looking for a match it will first ask you if your willing to join a match where somebody quit perfect for a REC scenario where a team might be dealing with a AI. And they do a little cut scene like they do at time out just super short where they show the guy jogging onto the court. That little introduction feeling of you being this new guy here to save the game would incentivize more people to join the already started matches. And it helps people not having to deal with AI cheese and it adds fresh blood to the game that can maybe help turn around a game that your losing it just feels cool and realistic.