Posted by Bill Baer on Friday, July 3, 2009 at 7:22 pm

Jimmy Rollins has a .575 OPS. CHONE projected him to put up a .794 OPS. To give you an idea as to just how far Rollins has fallon off the face of the planet, CHONE’s tenth-percentile projection (the most pessimistic) had him at .706. Rollins’ current OPS would have been somewhere around the second or third percentile, presumably — that’s how bad it’s been.

Why he’s been running this bad is a mystery. None of the plate discipline metrics found at FanGraphs and Baseball Reference are out of the ordinary, contrary to what you may think. His plate discipline stats match up with those in seasons past. The biggest change has been the lack of line drives and the abundance of fly balls: line drives are 6.5% below his career average and fly balls are 5% above.

There’s nothing fishy in the distribution of pitches he’s seen — everything’s within about a percentage point of his career averages. As we can see with the following charts from his recent o-for-28 streak, he’s been swinging at pitches around the strike zone; an obvious red flag would have been waved if he had been diving way out of the zone.

The lack of line drives, then, would seem to be mechanical. Check the following chart: he’s had fastballs right down the middle and all he’s done is hit them for fly balls; not line drives or home runs.

Unlike teammate Ryan Howard, Rollins’ offense has never been feared enough for opposing teams to employ a shift, so Jimmy hasn’t been bitten by a deflated BABIP in that regard. However, it is still abnormally low at .218. When you look at his BABIP on batted ball types, he’s been well below average on grounders and line drives.

Blaming his abnormally low BABIP on mere bad luck is too simplistic. It is more likely a combination of bad luck as well as hitting balls more weakly. The batted ball profiles don’t show you the various shades of power with which players make contact. Suffice it to say that there’s a vast difference in the success rate in ground balls depending on the type of contact made. Overall, Rollins has been making weaker contact, but there’s no data to flesh that out.

Lastly, despite still having a good idea of the strike zone, Rollins’ walk rate is down more than 4% from last season and 2% from his career average. This isn’t due to a poor approach at the plate, nor is it due to fewer opportunities: Rollins has had 59 plate appearances in which he has had three balls in the count, approximately 18% of his at-bats. Last season, he had 120 three-ball counts in 625 plate appearances, approximately 19% of his at-bats.

The likely explanation for that is pitchers are less willing to pitch around Rollins because, well, he’s making weak contact. He’s an easy out.

Diagnosing Rollins is a tricky issue, and everyone has a different prescription. The way he’s completely tanked is nigh on a statistical improbability, but here we are in June and the 2007 National League MVP has a .575 OPS.  The likely explanation isn’t mental (approach) or physical (injury); it’s mechanical (swing). Something many of us Phillies fans have loathed about Rollins since he’s been in the Majors is his blatant uppercut swing — it seems like he’s always trying to hit home runs rather than making solid contact via line drives, or at least putting the ball on the ground where his speed can be utilized.

There’s no doubt that both Rollins and the Phillies’ coaching staff have put in long hours trying to right the ship, and there’s also no doubt that there’s lots more work yet to come. Fixing Rollins, who usually gets the most plate appearances of any other hitter on the team since he bats lead-off, would go a long way towards fixing the Phillies’ offensive inconsistency. Of course, Rollins can neither start nor relieve, so he is but one of the problems facing the Phillies heading into the second half of the season.