Pro Football Focus looked at how the Green Bay Packers lined up on passing plays with TE Jermichael Finley and without. Here's the final analysis:
While I'm sure there is a reason for use of a second tight end when Finley is in the game, but it's not entirely obvious to me. For that second tight end, it usually comes at the expense of one of the fullbacks. Since the second tight end and full back are probably left in to pass block, I'm not sure why the that second tight end is a better choice. Maybe Mike McCarthy just prefers having an extra blocker on the line of scrimmage instead of in the back field.