Q:

Are the MVP achievements in Battlefield 3 stacked?

There are 3 MVP achievements in Battlefield 3, They are:

Most Valuable Player 
Finish as MVP in a ranked match

1st Loser
Finish as 2nd MVP in a ranked match

It's better than nothing!
Finish as 3rd MVP in a ranked match

If I unlocked the "Most valuable player" achievement, having not unlocked the other two, will the other two unlock as well?

A:

No they will not. You must specifically finish as the MVP that the achievement requires you to.
Finishing as MVP 1 will not unlock the achievements for MVP 2 or 3, you must finish as MVP 2 or 3 to unlock those achievements.

