Which players have most affected this year's pennant races? Here are some of the top surprises and disappointments that help explain where we are as we head into September.
SURPRISES
The right-hander's first season in Boston was a huge disappointment as he went 9-15 with a 4.92 ERA. This year, he's 17-3 with a 3.23 ERA. Yes, win-loss record is dependent on run support, but six games below .500 to 14 games over .500 is a 20-game swing. That obviously overstates his actual value. But in the same number of innings as last year, Porcello has allowed 34 fewer runs, even though offense has gone up leaguewide, and that has been worth 3-4 additional wins for the Red Sox.