Unfavorable action for Jackson

The Arizona Diamondbacks and their fans expected big things of Edwin Jackson this season after his trade to the desert this offseason. It seemed like the 1-2 punch of Dan Haren and Jackson, along with the possible return of Brandon Webb, would give the D-Backs a chance in the wide-open NL West. But Jackson is not the same guy we saw in Detroit last year, even with the move from the American to the National League.

What has caused Jackson’s slide and can a return to 2009 form be expected?

So far Jackson has taken advantage of the relatively punchless NL lineups, holding 8- and 9-hole hitters to a batting/slugging line of .143/.179. That’s an improvement from the .201/.262 line he posted last year in the AL. Of course that means that the first seven hitters are getting to him, and that’s primarily by not chasing his fastball.

Not So Fast

Even as Edwin Jackson throws more fastballs in the strike zone, hitters are offering at it less, especially when it's out of the zone.

As hitters are more selective with his heater this season, they are picking out the right ones. Opponents are ripping Jackson’s fastball, hitting .336 and slugging .560 against it, way up from .278 and .480 a year ago. The difference is even bigger when you take out the weak eighth and ninth hitters in the NL, as hitters one through seven are hitting .400 and slugging .670 against Jackson’s fastball. Velocity doesn’t seem to be a problem, as he’s averaging just 0.5 MPH less than last year.

However, there are two things that are having a bigger effect on Jackson this season: batting average on balls in play and fly ball rates. According to Baseball Reference, in 2009, Jackson had a slightly-better-than-average BABIP of .279, but that has skyrocketed to .359 so far this season.

Additionally, even as Jackson has increased his GB/FB rate from 0.66 to nearly 1.0, his infield-fly ball rate has plummeted from 16 percent last year to just four percent so far in 2010. This is not a good sign, and is reflected in his HR/FB rate, which has increased for the second straight season, up to 10.8 percent so far this year. In fact, he’s got three starts already this year where he’s gotten more ground balls than fly balls, after having five such starts all of last season.

Jackson pitches tonight against the Florida Marlins, who are middle-of-the-pack against fastballs so far this season. Perhaps if he gets a little bit of luck on balls in play, or some help from his defense, he might begin to get back on track.