something changed in 2007.
What changed? Here's a start:
| Season | GB% | HR/9 |
| 2002 | 34.50% | 0 |
| 2003 | 36.40% | 1.2 |
| 2004 | 33.40% | 1.51 |
| 2005 | 35.60% | 0.98 |
| 2006 | 32.70% | 1.3 |
| 2007 | 35.30% | 1.57 |
| 2008 | 45.90% | 0.48 |
| 2009 | 41.30% | 0.66 |
| 2010 | 41.90% | 0.68 |
2002-2007 GB% Average: 34.65%
2008-present: 43.03% -- a difference of 8.38% from the previous 5-6 years. What a change a groundball can make, huh?
data: fangraphs