Preview: Game #156, Diamondbacks @ Padres

Brandon McCarthy RHP, 5-9, 4.57

Eric Stults LHP, 9-13, 4.02

Diamondbacks line-up

1. Adam Eaton, RF
2. A.J. Pollock, CF
3. Paul Goldschmidt, 1B
4. Martin Prado, LF
5. Aaron Hill, 2B
6. Matt Davidson, 3B
7. Wil Nieves, C
8. Cliff Pennington, SS
9. Brandon McCarthy, P

The last five games, the Diamondbacks have been on fire: they've batted .344 and averaged close to eight runs per game. Of course, a factor in that was Coors Field, which still ranks as the most hitter-friendly park in baseball this year. But it's a case of from the sublime to the ridiculous for Arizona, because the same list has Petco ranked 30th. "Hang on," you may be thinking. "Didn't the Padres move the fences in this year? Wasn't that supposed to improve things for hitters there?" Well, both yes and no...

It has certainly made the park more homer-friendly. This year, Petco has seen one home-run about every 39 at-bats, a sharp increase over the same figure in 2012, when it was one every 49 at-bats. And, lo, the Park Factor for home-runs has improved from 0.626 to 0.978, almost normal. However, those home-runs haven't come out of nowhere: they are mostly hits that would have previously been doubles, and the park factors for those at Petco have completely cratered, slumping from 0.960 to 0.775. As a result, the overall number for Petco hasn't changed: it has actually dropped slightly, from 0.854 to 0.844. Seems there's more to how a park plays than its fences.

Looking at the dimension changes, one thing has played out as expected, and that's the way the shortened porches in just about all of right field have helped left-handed hitters. Here are the stats for all National League southpaws at Petco, comparing this year and last:

That's startling: If there are just two homers hit by left-handers in this last home series, there will be double the overall number from 2012 - likely in fewer at-bats. Quite a remarkable change, considering we're talking a reduction of only about 11 feet in right-field. Given the changes in left-field were less broad, affecting a smaller section of the park, you'd probably expect a lower, but still positive, bump in numbers for right-handed batters. Not so fast. Here are the actual figures, again for all NL right-handed hitters.

That's strange. Why would pulling the fences in cause a sharp decrease in overall offensive power numbers? One thing I noted, was a sharp decrease in BABIP for right-handed batters. It wasn't very good last year, being only .291 (league average = .300), but dropped further, to .278 (avg .297). The overall .284 BABIP, was the second-lowest in the NL, ahead of the Mets' Citi Field. This could be a temporary aberration. But it seems possible the adjustments in right-field have hurt right-handed batters more, shrinking the space available for non-homer outfield hits to the opposite field, without much compensatory help on the other side. But the downtick in RHB homers is kinda odd.