COD,
Let me begin by clarifying what "straggling is" it is the moment when you (the player) realize that the enemy has begun to spawn near you.
This is not science, despite the fact many players fail at straggling the spawn to your advantage. Here is what I have been experiencing for the last month of so:
As my team pushes into the enemy's spawn points, I remained behind them but in the middle (not in my spawn) but usually towards the center of the maps. Paying attention to where my team is, I can determine the enemies spawn is. So I adjust to prepare a surprise attack, I straggle the spawn and get a few kills, its the unaware enemy who are running towards their old spawn I prefer. But you have to prepare to fend for yourself.
If you learn how to use spawn towards your advantage, then stay behind and straggle them to death. Its effective and catches them off guard if done properly.