I was trying to play the Heroic Strike playlist yesterday, but over half of the times I have tried to play I either had a fireteam member go inactive, or drop out right at the beginning. And not once did matchmaking find a replacement to get the fireteam back to 3. I suggest the game kicks a player much sooner from a fireteam when he is inactive, either by time spend not moving, or how far ahead the rest of the team is. Also the matchmaking has to be much better at finding that third player to fill out the fireteam if someone drops. It got very ridiculous.