I've designed an informal index to rank relievers according to the % of leads they converted. The index should be read like ERA+ or OPS+, where 100 = average. I calculate each individual's leads converted % against the league average %. So, in the 2007 NL, where the league average leads converted was .085085, I divide the player's % of leads converted by the league average, and then multiple that number by 100 (i.e., 85085 / 85085 = 1 x 100 = 100 = league average).

Here's a list of relievers with 10 or more leads opportunities from the NL in 2007, arranged according to number of leads opportunities, and then according to their % of leads converted.

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(An example of the calculation is... Brian Fuentes (28/35, 80%), so 80000 / 85085 = 0.94 x 100 = 94.0. This number is simply an index number used to more accurately compare relievers according to each other and according to league average. It should be read simply like ERA+ or OPS+, where 100 = average. +100 = above league average, -100 = below league average.).

40-54 opportunities

Brandon Lyon, Ari: 37 leads converted (35 hld, 2 sv)           40 opportunities          108.7

Kevin Gregg, Fla: 38 leads converted (32 sv, 6 hld)              42 opportunities          106.3

Takashi Saito, LAD: 40 leads converted (39 sv, 1 hld)          44 opportunities          106.8

Heath Bell, SD: 36 leads converted (34 hld, 2 sv)                 40 opportunities          105.7

 

Jose Valverde, Ari: 47 leads converted (47 sv)                      54 opportunities          102.3

Francisco Cordero, Mil: 44 leads converted (44 sv)               51 opportunities          101.4

Jon Rauch, Was: 37 leads converted (33 hld, 4 sv)                43 opportunities          101.1

Trevor Hoffman, SD: 42 leads converted (42 sv)                  49 opportunities          100.7

Jonathan Broxton, LAD: 34 leads converted (32 hld, 2 sv)   40 opportunities          99.9

Chad Cordero, Was: 38 leads converted (37 sv, 1 hld)          47 opportunities          95.0

 

40-54 opportunities: 393 leads converted / 450 opportunities, .87333                       102.6

In this first group, we see a small group of relievers that were able to face a lot of leads opportunities because of their role. The interesting thing about these relievers is that while only two of them were below league average as a whole (Broxton and Chad Cordero), six of the ten relievers were below the group average, meaning that although they were mostly better than a leaguer average NL reliever, most of the members of this group did not do their job as well as the average of the group. This suggests, in some ways, that it is very tough to find a closer that converts leads at 90% or higher (which Lyon, Gregg, Saito, and Bell accomplished). Meanwhile, closers that convert fewer than 90% of their leads are much less valuable because not only are they closer to league average, and therefore more easily replaced, but they are also not converted leads at a % demanded by the role.

According to the 2007 NL, relievers that face 40-54 opportunities should convert leads above 87%.

31-39 opportunities

Jason Isringhausen, StL: 32 leads converted (32 sv)              34 opportunities          110.6

Manuel Corpas, Col: 35 leads converted (19 sv, 16 hld)        38 opportunities          108.3

Derrick Turnbow, Mil: 34 leads converted (33 hld, 1 sv)       37 opportunities          108.0

Matt Capps, Pit: 33 leads converted (18 sv, 15 hld)              36 opportunities          107.7

Tony Pena, Ari: 32 leads converted (30 hld, 2 sv)                 35 opportunities          107.5

Rafael Soriano, Atl: 28 leads converted (19 hld, 9 sv)           31 opportunities          106.2

Ryan Dempster, ChC: 28 leads converted (28 sv)                 31 opportunities          106.2

Bob Howry, ChC: 30 leads converted (22 hld, 8 sv)             34 opportunities          103.7

 

Billy Wagner, NYM: 34 leads converted (34 sv)                   39 opportunities          102.5

Brad Hennessey, SF: 32 leads converted (19 sv, 13 hld)       37 opportunities          101.6

David Weathers, Cin: 33 leads converted (33 sv)                  39 opportunities          99.4

Ryan Franklin, StL: 26 leads converted (25 hld, 1 sv)          31 opportunities          98.6

Chad Qualls, Hou: 26 leads converted (21 hld, 5 sv)             32 opportunities          95.5

Brian Fuentes, Col: 28 leads converted (20 hld, 8 sv)            35 opportunities          94.0

Brad Lidge, Hou: 26 leads converted (19 sv, 7 hld)              34 opportunities          89.9

 

31-39 opportunities: 457 leads converted / 523 opportunities, .87380                       102.7

  20-28 opportunities

J.C. Romero, Phi: 22 leads converted (22 hld)                       23 opportunities          112.4

Pedro Feliciano, NYM: 20 leads comverted (18 hld, 2 sv)    22 opportunities          106.8

Matt Lindstrom, Fla: 19 leads converted (19 hld)                  21 opportunities          106.3

Brett Myers, Phi: 24 leads converted (21 sv, 3 hld)               27 opportunities          104.5

Brian Shouse, Mil: 22 leads converted (21 hld, 1 sv)             25 opportunities          103.4

Saul Rivera, Was: 22 leads converted (19 hld, 3 sv)              25 opportunities          103.4

Justin Miller, Fla: 17 leads converted (17 hld)                       20 opportunities          99.9

Aaron Heilman, NYM: 23 leads converted (22 hld, 1 sv)      28 opportunities          96.5

A. Alfonseca, Phi: 23 leads converted (15 hld, 8 sv)             28 opportunities          96.5

 

Dan Wheeler, Hou: 17 leads converted (11 sv, 6 hld)            21 opportunities          95.1

Tom Gordon, Phi: 20 leads converted (14 hld, 6 sv)              25 opportunities          94.0

LaTroy Hawkins, Col: 18 leads converted (18 hld)               23 opportunities          91.9

Renyel Pinto, Fla: 17 leads converted (16 hld, 1 sv)              22 opportunities          90.8

Bob Wickman, Atl: 20 leads converted (20 sv)                      26 opportunities          90.4

Jorge Julio, Col: 16 leads converted (16 hld)                         21 opportunities          89.5

Salomon Torres, Pit: 17 leads converted (12 sv, 5 hld)          23 opportunities          86.9

Scott Linebrink, SD: 16 leads converted (15 hld, 1 sv)         22 opportunities          85.5

Shawn Chacon, Pit: 13 leads converted (12 hld, 1 sv)           20 opportunities          76.4

 

20-28 opportunities: 346 leads converted / 422 opportunities, .81991                       96.3

I put these two groups together because they are a study in contrasts. It seems that the relievers that faced 31-39 opportunities were actually the best relievers in the NL of those that faced 20 or more opportunities. Again, like the higher appearance closers, their role requires a higher lead conversion %, and they need to do their job at a high level. Unlike the higher appearance relievers, however, these relievers are more readily available, and it seems to be easier to find a reliever that faces 31-39 leads and does their job well than a reliever that faces 40-54 leads and does their job well. Perhaps this suggests something about how managers use their bullpen; maybe all relievers should be provided a lower number of appearances with a lead, in the hopes that more members of the bullpen can participate in a leads converted opportunity, and more relievers can do their job well.

By contrast, the 20-28 group was the worst of those relievers that faced 20 or more leads opportunities. As a whole, this group was below league average, meaning that their level of production is very easily replaced on any given team in the NL. This group is full of a range of good middle innings set up men that simply do not face a ton of leads, but do their jobs very well (Romero, Lindstrom, Feliciano, Shouse, and Rivera), and closers that do not face a lot of opportunities, or were bad at their job and were replaced (Myers, Gordon, Wickman).

I think that the lower leads converted% of the 20-28 group reflects managerial usage of relievers more than any other group. What is suggests to me is that by saving their better relievers for later in the game, managers then use relievers that are not as good in the middle innings, and these are the relievers that face 20-28 leads opportunities a year. They're not as good as top closers and set-up men, so they face less high leverage situations to begin with, and they also face fewer appearances because a starter is more likely to make it into the 6th or 7th than into the 8th or 9th. All of these factors taken together create a below average group from 20-28. I'd suggest that this is the aspect of bullpen management that needs to change the most.

10-19 opportunities

Joe Beimel, LAD: 17 leads converted (16 hld, 1 sv)              17 opportunities          117.6

Damaso Marte, Pit: 15 leads converted (15 hld)                    15 opportunities          117.6

Will Ohman, ChC: 13 leads converted (12 hld, 1 sv)             13 opportunities          117.6

Lee Gardner, Fla: 11 leads converted (9 sv, 2 hld)                11 opportunities          117.6

Ray King, Was: 10 leads converted (10 hld)                          10 opportunities          117.6

Doug Brocail, SD: 10 leads converted (10 hld)                     10 opportunities          117.6

Joe Smith, NYM: 10 leads converted (10 hld)                       10 opportunities          117.6

Carlos Marmol, ChC: 17 leads converted (16 hld, 1 sv)        18 opportunities          110.9

Randy Flores, StL: 15 leads converted (14 hld, 1 sv)                        16 opportunities          110.2

Tyler Yates, Atl: 15 leads converted (13 hld, 2 sv)                16 opportunities          110.2

Brian Wilson, SF: 15 leads converted (9 hld, 6 sv)                16 opportunities          110.2

Matt Wise, Mil: 14 leads converted (13 hld, 1 sv)                 15 opportunities          109.7

S. Schoeneweis, NYM: 13 leads converted (11 hld, 2 sv)     14 opportunities          109.1

T. Tankersley, Fla: 17 leads converted (16 hld, 1 sv)             19 opportunities          105.2

Carlos Villanueva, Mil: 17 leads converted (16 hld, 1 sv)      19 opportunities          105.2

 

Jack Taschner, SF: 13 leads converted (13 hld)                     15 opportunities          101.9

Trever Miller, Hou: 13 leads converted (12 hld, 1 sv)            15 opportunities          101.9

Russ Springer, StL: 11 leads converted (11 hld)                    13 opportunities          99.4

Steve Kline, SF: 11 leads converted (9 hld, 2 sv)                  13 opportunities          99.4

Jesus Colome, Was: 13 leads converted (12 hld, 1 sv)           16 opportunities          95.5

Kevin Correia, SF: 12 leads converted (12 hld)                     15 opportunities          94.0

Jared Burton, Cin: 11 leads converted (11 hld)                      14 opportunities          92.3

Mike Stanton, Cin: 10 leads converted (10 hld)                     13 opportunities          90.4

A. Benitez, Fla: 11 leads converted (11 hld)                          16 opportunities          80.8

Cla Meredith, SD: 10 leads converted (10 hld)                      15 opportunities          78.4

 

10-19 opportunities: 324 leads converted / 364 opportunities, .89011                       104.6

The relievers that face 10-19 opportunities have the highest percentage of any group of NL relievers because, let's face it, they face fewer opportunities and thus probably have more leverage to succeed. They are probably less likely to work multiple days in the week in this group, and they are also relievers that are used for multiple tasks. Some that snuck into this group, like Wilson, Marmol, and Beimel, have the chance of being better relievers than this group indicates, and simply faced a different opportunity in the bullpen for 2007. They will all likely face different roles throughout 2008.