That headline is neither literally nor completely true.
Of course they do have a choice, and in fact some of them will make different choices. In fact, long-time BBWAA member and award voter Sean McAdam has studied on it, and he voted for Mike Trout. But I am almost certain that the weight of history and emotion and biases have left the MVP voters, as a group, with little choice but to vote for Miguel Cabrera this year.
If there are two things we know about MVP voters, it's that
1. they're impressed by "run producers" -- that is, big RBI guys -- on first-place teams, and
2. they're impressed by shiny objects.
I'm not even sure how true the second of those is, though. In 1994, Tony Gwynn batted .394 and finished seventh in the MVP balloting. In 1998, Mark McGwire hit 70 home runs and finished second in the MVP voting. A year later, McGwire hit 65 home runs and led the National League with 147 RBI, and finished fifth in the balloting.
None of those shiny objects led to the postseason. Now, maybe the objects just weren't quite shiny enough. Maybe Gwynn would have actually won the award if he'd batted .400. Maybe McGwire's 70 home runs were just slightly tarnished by Sammy Sosa's 66 homers in the same season; Sosa was named Most Valuable Player in a landslide.
If you take some of the MVP voters at their word, though, they're might impressed by Miguel Cabrera's Triple Crown. It's sort of the ultimate shiny object, considering that most of us literally cannot remember another Triple Crown winner; after all, it's been 45 years. But then again, Mike Trout is a shiny object unto himself and literally none of us have ever seen a rookie season as brilliant as Trout's.
If Cabrera had simply led the American League in runs batted in, with the Tigers finishing behind the White Sox, he wouldn't have been a popular MVP candidate. If he'd finished second in runs batted in, with the Tigers finishing ahead of the White Sox, he would not have been a popular MVP candidate.
What if Cabrera had led the league in RBIs while the Tigers won the A.L. Central -- which both happened, of course -- but he didn't win the Triple Crown? Obviously, we can't know for sure. A lot of RBI leaders on division- and pennant-winning teams have beat out a lot of superior players for the MVP Award, but few of those superior players were as superior as Mike Trout.
What's obvious is that there has long been a huge bias among the voters toward the RBI guys on playoff teams. Marc Normandin mentioned a a few of the more egregious cases here, but there have been many others. In 2006 there was Justin Morneau, who wasn't the best player on his team, and Ryan Howard. In 2004 there was Vladimir Guerrero. In 1996 and '98, there was Juan Gonzalez. In 1998 there was Sammy Sosa. In 1995 there was Mo Vaughn. In 1989 there was Kevin Mitchell, who wasn't the best player on his team. In 1985 there was Don Mattingly, who wasn't the best player on his team. In 1979 there was Don Baylor, who wasn't the best player on his team.
The list goes on and on and on and on and on and on, back to the 1960s at least.
Today's voters can make all the arguments for Miguel Cabrera they like, and when you consider all the intangibles I can't tangibly say they're wrong. But given the history of the Most Valuable Player voting, it's hard to see how voting for Miguel Cabrera in 2012 doesn't fit into a decades-long pattern that looks, with the benefit of hindsight, like abject foolishness.