This is a giant issue. We sit in ques for however long, end up in a game where the game is almost over and we reap no reward from this. The suggestion is to revamp the matchmaking / find quick game algorithm to cross match players to a new game. In progress games have been happening almost all day long and I have gained almost 0 exp in 2 hours because of such.
This is pretty frustrating for many people including myself. I'm attempting to gain as much exp as possible to unlock some of the outfits for better selection of camo use etc, and unfortunately I'm not gaining any exp in 2 hours. That's a straight bogus for the majority of the players I've come across since they've all been talking about it in game when joining on a match in progress.
The major suggestion is to make sure if we join a match in progress, it's not the last round, but rather maybe just after the start / midway through the first round so we can gain some experience towards our level up system.