Sinister Problems: The D-backs vs. left-handed pitching

Watching Randy Wolf, Jamie Moyer and Cliff Lee mow down the Diamondbacks over the past few days provided some perfect examples of the problems the team has had facing southpaws this year. The loss means the team record is just 12-24 when a left-hander starts for the opposition - no team has a lower winning percentage in all of baseball. That's a significant change from last season, where Arizona were a solid 28-20.

What has happened to cause this change in fortunes? And is there a problem which needs to be addressed if the team is to compete in 2010? Details after the jump.

One key factor is that the team has become a great deal more left-handed than it was. In particular, the loss of Conor Jackson and Eric Byrnes, and the replacement of Chris Snyder and Chris Young - each right-handed at the plate - have helped skew things that way. Last year, 64% of the Diamondbacks' plate-appearances came from the right-hand batters' box, and only two of our ten most active batters were pure left-handers - Chad Tracy and Stephen Drew. This season, the overall fraction is below league average (56%), all the way down at 54%, and the number  of most active players is up to four, with the addition of Miguel Montero and Gerardo Parra to the list.

This alone would tend to have a significant impact because, as we've discussed before, right-handed batters are on average almost sixty points of OPS better against left-handed pitchers, than left-handed batters. The following chart is the splits by pitcher for the Diamondbacks, this year and last. The figure in square brackets after OPS is the National League average for that split over the same time.

A couple of things to note here. Our results against RHP have improved, just not by as much as our results against LHP have dropped [the numbers were a lot closer before the lawyer's firm of Wolf, Moyer and Lee got to us]. The overall impact is an OPS ten points better in 2009 than it was, which has been reflected in a slightly-improved offensive output, from 4.44 runs/game last year, to 4.49 this season. With most pitchers being right-handed, having a lot of left-handed batters in your line-up is not a bad thing, everything else being equal. And our record against RHP has improved, from 54-60 to 42-43, not enough to erase the left-handed drop-off, though it does negate it somewhat.

What's curious is that we have almost the same OPS against both kinds of pitchers, but the overall level of runs which results, is radically different. In the 36 games started by lefties, the Diamondbacks scored a total of 134 runs - 3.7 per game. Against right-handed starters, it's more than a run higher. At first, I though this might be because the running-game does not show up in OPS, and is more likely to be a factor against a right-handed starter. However, more of our stolen bases have come vs. LHP: 28.4%, in only 25.1% of plate appearances. So I'm not quite sure why the team has such trouble scoring.

If we look at the individual splits on the season, we can perhaps get a few clues: some of our left-handed batters have been really struggling against their counterparts. Top of that list would be clutch wunderkind Gerardo Parra, who has a truly dreadful line of .212/.239/.212, an OPS of .451 in 90 plate appearances. He has no extra-base hits off a southpaw in his career, and only two walks in 87 at-bats. This is perhaps the biggest road-block to him becoming a full-time outfielder in 2010. The good news is, his minor-league splits aren't as bad - his OPS is .753 vs. LHP, 75 points below the RHP number, and he is still young, so perhaps he may develop. While I've no problem with him playing, since he needs to learm somewhere, the #3 spot seems extremely inappropriate.

Stephen Drew is also batting .212, but does at least have some pop, with an OPS of .643, though this is still well below his career line, hitting .255 with a .720 OPS. More surprisingly, while one of our catchers is struggling badly against LHP, it's not the one you'd probably think. No: Miguel Montero is batting over .300, though has only one walk and one home-run, in 53 at-bats. It's Chris Snyder - 9-for-53 - who isn't hitting them; conversely, he has more than twice as many walks as hits. If we could just combine him and Miggy... A fiendish teleportation experiment gone awry, that should do the trick. Where's Jeff Goldblum when you need him?

Mark Reynolds is doing perfectly well: his OPS of .953 against left-handed pitching is right there with the .977 ones facing right-handed ones. The rest of our first-base platoon, however, can't say the same, with Chad Tracy and Josh Whitesell combining to go 11-for-66, a .167 clip - Dan Haren has more hits off LHP this year than Whitesell. Of course, the main alternative at the position for 2010 is another left-hander in Brandon Allen, but his minor-league career splits are not bad, only 24 points separating the OPS numbers. For the moment, here's the line-up I'd suggest for Arizona against a lefty.

1. Trent Oeltjen, LF
2. Alex Romero, RF
3. Ryan Roberts, 3B
4. Mark Reynolds, 1B
5. Miguel Montero, C
6. Stephen Drew, SS
7. Rusty Ryal, 2B
8. Gerardo Parra, CF
9. Pitcher

The return of Justin Upton should help significantly, as our young prodigy has absolutely murdered left-handed pitching this season, to the tune of .388/.469/.812 - that's a 1.281 OPS. Ryan Roberts is another who has been death to southpaws, with a .342 average and an OPS of about a thousand, which is why I  would currently stick him in the #3 spot - on his return, Upton would replace RR there. For 2010, Chris Young would seem a better option in center than Parra, based on the latter's results so far - some kind of long-term platoon may be in the team's interests.

[Stats except for W/L are through the end of Tuesday]