I'm sorry, but that just makes no sense. Soriano's play has been valuable, while the play of his teammates has been terrible. One player cannot control the play of his team. He most certainly can be valuable on a last place team. They could be much worse without Soriano.
What's not fair is someone getting the benefit of the doubt because he's blessed with being on a team with great pitching, or excellent surrounding talent. That surrounding talent is the real difference between the wins and losses of the teams battling for a playoff birth and those with no chance (see Nationals). If you want to disqualify a player from MVP status because his team isn't in contention, then you might as well argue that one person can overcome an absolute lack of team talent and force his team to win.
The measure of an MVP should be: How much worse would that player's team be without him? Being on a losing team doesn't disqualify you, but it does dampen the effect of an individual's play. That's why it will be so hard for Soriano. He will have to blow away the competition like ARod and Andre Dawson did in the past.
All that being said, I still believe Pujols will win, as Beltran and Wright steal votes from each other. Soriano will most likely end up 2nd or 3rd. I think Ryan Howard could make a late push too.