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One of the most important differences between a starter’s job and a reliever’s is that relievers often have to enter the game with a crisis already brewing. In addition to the normal pitching responsibility of preventing batters from coming around to score, the reliever often has the task of preventing runners already on-base from touching home as well. His handling of those inherited runners is a critical part of his overall job performance, but it’s one that gets very little attention in mainstream baseball coverage. It doesn’t show up in ERA or any other widely available stat; and while you’ll occasionally hear a mention of a reliever’s “stranded runner percentage,” that’s not a number you’ll find listed in the tables of your morning paper.

Besides, just measuring the percentage of inherited runners that were stranded (or the percentage that scored) doesn’t paint a complete picture of the inherited runner issue. For one thing, in many cases those inherited runners are still on base when the reliever leaves the game. If Joe LOOGY comes in the game with a runner on second and none out, he strikes his batter out, and then gets taken out of the game, it doesn’t make sense to count that runner as “not stranded” or “not scored”. To see this in practice: Tom Martin was easily the majors’ best reliever in percentage of inherited runners scored, according to STATS Inc.’s list, and Buddy Groom was the AL leader. But those ratings of Martin and Groom, both situational lefties, were inflated by the fact that they didn’t finish innings nearly as often as the average reliever. They didn’t allow their inherited runners to score partly because they were taken out of the game before they had a chance to.

To get around that problem and others, it makes sense to think of inherited runners in terms of potential runs. When a reliever comes into the game with a runner on second and none out, there’s a 65% chance that runner on second will score. If the reliever gets out of the inning without him scoring, he’s saved 0.65 inherited runs, compared to average pitching. If the runner does score, he’s “saved” -0.35 inherited runs. And if he strikes out a batter and then leaves the game, lowering the chance of the runner scoring to 41% in the process, he’s saved 0.65 – 0.41 = 0.24 inherited runs. That’s the basic approach to inherited runners we take in our reliever report. It gets a little more complicated than that since we adjust for park difficulty, but you can get the gory formulas in the glossary. The rankings in those reports show the best and worst each season at handling inherited runners. But because of the relatively small sample sizes, those lists can be subject to some fluctuation from year-to-year. What we want to look at in this article are the guys who have a long-term track record of successfully handling inherited runners, running back to 1998 (i.e., all the years for which I have the data).

Here are the top relievers in Inherited Runs Prevented (IRP) for the past six years:

Reliever            IRP      NIRP
Scott Sullivan     22.4      36.8
Ricardo Rincon     21.2      31.3
Steve Reed         19.1      45.7
Jim Mecir          17.6      43.3
Keith Foulke       17.3     110.8
Jeff Zimmerman     15.3      45.8
Dave Veres         14.7      43.3
Mike Stanton       13.9      30.9
Buddy Groom        13.8      31.6
Curt Leskanic      13.0      44.3

The right column is a measure of the remainder of his run prevention (Non-Inherited Runs Prevented), i.e., how well he keeps the batters he faces from scoring. We’ll get to that column in a second.

New Royal Scott Sullivan may not be the pitcher he once was in his Reds heyday, but he’s still the king of inherited runners for recent times. The 22.4 Inherited Runs Prevented represent runs that would have been charged to other Reds pitchers if they’d gotten average relief. Those guys owe him a beer.

Unlike most reliever rankings, this one contains virtually no closers. Even the pitchers who did spend significant time as closers did most of their inherited runners damage as middle men before getting the ninth inning job–Keith Foulke in 1999, Jeff Zimmerman in 2000. As we’ll see in a second, it’s not surprising to see the closers get shut out of this list, since they’re not usually used to put out mid-inning fires.

The other interesting thing about the list is that it contains the bulk of the A’s 2003 bullpen. Ricardo Rincon, Jim Mecir, and Foulke all did most of their inherited runners work before joining the A’s, but it’s still an indication that the A’s appreciate things that other teams overlook–maybe not inherited runners per se, but the component stats that lead to good inherited runner numbers. And while he doesn’t appear on this list, the fourth major cog of the 2003 A’s pen, Chad Bradford, was last year’s inherited runners champion.

On the other side of the spectrum, here are the worst relievers at handling inherited runners since 1998:

Reliever            IRP      NIRP
Tim Worrell       -22.0      33.2
Nelson Cruz       -19.0       7.3
Chuck McElroy     -16.2      -8.7
Mark Petkovsek    -14.8       1.4
Scott Radinsky    -13.8       0.8
Carlos Almanzar   -13.2     -16.6
Felix Rodriguez   -13.0      40.0
Carlos Silva      -12.8       3.4
Mike Bynum        -12.2     -11.3
Pedro Borbon      -11.8     -21.9

Tim Worrell is an odd case. He’s a quality reliever overall, but last year marked the sixth consecutive season he was below average with inherited runners. I’ve followed his strange Jekyll-and-Hyde performance for several years now, but I still don’t have a good explanation for it. It’s not like he’s a terrible pitcher with runners on base; his 2001-2003 splits show him as quite a bit better with runners on than with the bases empty. It seems like he just loses it when it’s someone else’s runners he has to deal with.

Now to that rightmost column. The Non-Inherited Runs Prevented numbers show that all of the top relievers at stranding inherited runners are also very good at preventing their own runners from scoring. Each one of those top 10 is not only above average, but way above average in the non-inherited component of their pitching. The story is a little more complicated in the second table, but overall the pitchers on that list are much worse in both the non-inherited and and the inherited components of run prevention. The lesson may be an obvious one, but it’s worth pointing out anyway: Good relievers–that is, the ones with low ERAs–prevent inherited runs as well as their own. And because ERA doesn’t account for the inherited runs they prevent, it’s generally underrating the best middle relievers. The correlation between Inherited Runs Prevented and Non-Inherited Runs Prevented is a fairly strong 0.38, and that’s without accounting for differing levels of opportunity.

Speaking of which, it will come as no surprise that different relievers face widely different levels of opportunity when it comes to preventing inherited runners from scoring, but we’ll quantify it anyway. Here are the leaders and trailers in inherited runners per relief appearance since 1998 (minimum 200 appearances):

Rank Reliever        Throws      IRnrs/App
1    Mike Venafro       L           0.95
2    Mike Holtz         L           0.91
3    Tim Crabtree       R           0.88
4    Dan Plesac         L           0.88
5    Jesse Orosco       L           0.88
6    C.J. Nitkowski     L           0.86
7    B.J. Ryan          L           0.85
8    Mike Myers         L           0.83
9    Mark Petkovsek     R           0.82
10   Rich Rodriguez     L           0.81
118  Troy Percival      R           0.27
119  Robb Nen           R           0.27
120  Mike Williams      R           0.26
121  Jason Isringhausen R           0.25
122  Matt Mantei        R           0.25
123  Roberto Hernandez  R           0.24
124  Bob Wickman        R           0.24
125  Jeff Shaw          R           0.23
126  Billy Koch         R           0.22
127  Billy Wagner       L           0.20

The trend here is very clear. Middle relievers, particularly one-out lefties, deal with far more inherited runners than closers. LOOGY Mike Venafro saw almost five times the number of inherited runners as closer Billy Wagner over the past six years.

So while it’s informative to look at the raw number of inherited runs prevented by relievers, it can also be unfair to talented closers who simply don’t have the opportunity to prevent inherited runners from scoring that middle relievers have. To correct for this, we can normalize the Inherited Runs Prevented measure by the level of opportunity. Here we’ll use the number of inherited runners as our measure of opportunity; there are other possible measures, but they’re more difficult to explain and they don’t make much difference in the final numbers.

Here are the top and bottom relievers of the past six years in Inherited Runs Prevented per 50 inherited runners (I picked 50 because that’s a healthy number of runners for a middle reliever to inherit over the course of a season):

Rank Reliever        IRP/50Rnr
1    Bob Wickman        6.3
2    Keith Foulke       5.5
3    Trevor Hoffman     5.0
4    Jim Mecir          4.9
5    Curt Leskanic      4.8
6    Tom Gordon         4.7
7    Byung-Hyun Kim     4.5
8    Ricardo Rincon     4.4
9    Scott Sullivan     4.1
10   Dave Veres         4.0
118  Felix Rodriguez   -3.3
119  Matt Herges       -3.3
120  Dennys Reyes      -3.3
121  Ugueth Urbina     -3.5
122  Jeff Fassero      -3.7
123  Antonio Alfonseca -3.8
124  Brian Boehringer  -3.9
125  Mark Petkovsek    -4.1
126  Chuck McElroy     -4.8
127  Tim Worrell       -5.1

This list does a better job of putting all relievers on a level playing field. Many of the middle relievers we saw above show up again, but correcting for opportunity also makes it possible for closers to have extreme ratings–both at the top (Trevor Hoffman, Byung-Hyun Kim) and at the bottom (Ugueth Urbina).

There are plenty of interesting topics related to inherited runners that I haven’t touched on here: Exactly how much does ERA underrate top middle relievers? Should managers use closers to handle more mid-inning situations? But those will have to wait for future articles.

Thank you for reading

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