One of the huge factors in the Indians' success last season was their ability to field the ball. In 2005, the Indians were among the best in baseball in turning balls in play into outs. And that certainly helped a staff which was largely made up of contact pitchers.
This season, though, is a different story. The Indians currently rank 26th in baseball in Defensive Efficiency. And that has affected the pitching, especially Jake Westbrook and Jason Johnson. The Hardball Times tracks a statistic called Fielding Independent Pitching, which essentially tells what a pitcher's ERA would be if he had a league-average defense behind him. Westbrook's FIP is 4.06, a difference of 1.87 runs, and Johnson's is 3.84, a difference of 1.98. Paul Byrd has also been hurt by his defense; his FIP is 1.52 runs less than his "real" ERA.
So who have been the culprits? Using Baseball Prospectus' FRAR:
Eduardo Perez: -1
Ben Broussard: +1
Ronnie Belliard: -1
Jhonny Peralta: +10
Aaron Boone: -1
Jason Michaels: 0
Grady Sizemore: +6
Casey Blake: -1
In most cases, it's been the infield that has let the ground-ballers down. Ronnie Belliard has dropped off considerably from his 2005 defense; last season, he ended up with +29 FRAR. Fielding runs are accumulated over the course of a season, so comparing last year's totals with this year's numbers isn't entirely relevant. We can get an idea of how these numbers project by using BPro's RATE statistic:
(100 is league-average)
Perez: 92
Broussard: 100
Belliard: 84
Peralta: 119
Boone: 87
Michaels: 94
Sizemore: 106
Blake: 91
Given that both Westbrook and Johnson have groundball percentages over 60%, a poor infield defense has definitely hurt them. This isn't to say that Westbrook and Johnson have been good pitchers thus far, but it does put things in perspective.