The left-on-base conundrum

Stranding runners is a necessary accomplishment for any successful big league pitcher. After all, working out of jams is something a pitcher is tasked with nearly every time he takes the mound, and giving up a long ball to a hitter with runners on first and second brings a far different result than getting that hitter to ground out meekly to second base.

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So leaving runners on is crucial for any hurler, although some starters are far better at it over the course of a season than others. The major league average left-on-base percentage in 2013 was 73.5%, but any number of pitchers posted an LOB% far below or above this mark. Yu Darvish led the league with an 83.9% LOB%, the best since J.A. Happ’s 85.2% in 2009, while Edwin Jackson trailed all other starters, stranding runners at a lowly 63.3%.

What makes a particular pitcher good at leaving men on base is up to a number of different factors, though simply being able to generate whiffs is a great starting point. Yet LOB% is also partly dependent upon the laws of regression, with extreme numbers in either direction often regressing back towards the mean over a large enough sample. Regardless, some pitchers show an ability to outperform the rest of the league in LOB%, which can make analyzing the stat a fickle task.

Here are some of the pitchers who had an extreme LOB% in either direction last season along with my analysis of their chances at repeating their performances in 2014:

Yu Darvish – 83.9% LOB% in 2013 (Best in MLB)

Darvish’s name atop this list shouldn’t come as a surprise to most baseball fans. After all, the best pitchers at stranding runners are often simply some of the best pitchers period, as Darvish, Hisashi Iwakuma, Zack Greinke, Clayton Kershaw, and Jose Fernandez all ranked within the top 10 in LOB% in 2013. Yet Darvish is even better equipped at stranding runners than most due to his ability to generate strikeouts. The right-hander led baseball with a 32.9% strikeout rate last season, and according to Brooks Baseball, had six different pitches that yielded a whiff/swing rate of at least 20%. Darvish also pitches from the stretch on a full-time basis, making any mechanical adjustments that often come with switching to the stretch with men on base a moot point. I wouldn’t bet on Darvish posting another 83.9% LOB%, but given his elite strikeout ability, he should be among the league leaders in the category once again in 2014.

Chris Tillman – 80.5% LOB% (6th in MLB)

The Orioles right-hander saw his LOB% rise to 80.5% last year after a more normal 71.4% in 2012, something that should immediately spark off alarm bells. Significant increases like that are almost certain to correct themselves over a larger sample, and there is little in Tillman’s track record that suggests he can replicate his 2013 performance. The 25-year-old has just one pitch (his curveball) that yielded above-average results last season, and his 21.2% strikeout rate was just slightly better than league average. Tillman’s elevated LOB% was a big reason why he outperformed his FIP last year, and I would bet that is 3.71 ERA is due to rise this season.

Edwin Jackson – 63.3% LOB% (Last in MLB)

On the other end of the spectrum, Jackson was the worst pitcher in the league at stranding runners in 2013, struggles that no doubt contributed to his worst ERA (4.98) since 2007. Jackson’s strikeout rate (17.4%) took a worrisome dip below league average, but even then, his LOB% is certain to regress upward toward his career mark of 70.5%. The 30-year-old had a lot go wrong for him (he also finished with a .322 BABIP), and if his 3.79 FIP or 3.86 xFIP are any indication, Jackson should see better results in 2014, including in his strand rate. He’ll by no means become a LOB% leader in the Darvish mold, but Jackson is set to have a few things tick back in his favor during the season ahead.

Tim Lincecum – 69.4% LOB% (10th-worst in MLB)

Lincecum’s struggles with men on base have been well documented, with the Giants hurler posting a below-average LOB% for two straight seasons. From one perspective, Lincecum could be primed for serious improvement if his problems with stranding runners the past two years are the product of bad fortune. After all, the right-hander’s FIP (3.74) and xFIP (3.56) do indicate that his 4.37 ERA in 2013 could improve. I don’t quite buy that, however. Lincecum has performed worse when pitching from the stretch dating back to 2012, and his problems might be as much mechanical as anything else. He has never been one to have great control, and since his velocity and strikeout totals have decreased, his walk rate has only increased. That’s a bad combination, and one that leads to little success with men on base, or in any type of scenario for that matter. Even if Lincecum’s ERA regresses back towards his FIP, there is a good chance that he will continue to strand runners at a below-average rate moving forward.

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All statistics courtesy of FanGraphs unless otherwise noted.

Alex Skillin is a writer and editor at Beyond the Box Score and also contributes to SB Nation's MLB newsdesk. He writes, mostly about baseball and basketball, at a few other places across the Internet. You can follow him on Twitter at @AlexSkillin.