October 14, 2004

Starters vs. Relievers

The Changing Distribution of Pitching Performance

by James Click

Everyone loves plate discipline. Plate discipline allows hitters to control the strike zone, increasing his chance of getting a better pitch to hit. Getting a better pitch in turn increases the chances of putting the ball in play with authority rather than just simply putting it in play. Walks, and consequently the almighty on-base percentage, increase with plate discipline. Pitch counts increase, allowing teams to drive a starter from the game and get into the weaker parts of the bullpen.

This final point is a positive for the offense, but it is based on two assumptions. First, that the opposing pitcher is on a pitch count. While certain pitchers occasionally break through the upper layers of commonly acceptable pitch counts, very few starters will remain in the game past 110-120 pitches. Although the occasional Randy Johnson (162 pitches in 2000), Jason Schmidt (144 this year), or Mark Redman (147 in 2003) will break this mold, it generally holds true.

The second assumption is that the pitchers in the bullpen are inferior to the starter. This belief has largely been based on how teams have traditionally built their bullpens. As teams were transitioning from the idea that starters should pitch the entire game, they placed those pitchers who were not good enough to start in the pen. The idea of a dominant relief pitcher began to take hold in the 1960s and 1970s and, as such, the quality of relief pitchers improved.

However, most relievers were still washed-out starters. As bullpen size and usage has increased in the past 20 years, more and more players are transitioning to relief pitching earlier in their career. Now it’s not uncommon for teams to select college relievers near the top of the draft (Bill Bray and Huston Street being two of the most recent examples). Still, very few players grow up wanting to be a LOOGY (Left-Handed One Out guY, thanks John Sickels), so at some point, the better players are likely still to be channeled towards starting.

It’s not working. On average, bullpens have now surpassed the average starting pitcher in terms of quality of pitching. Consider the playoffs this year. If you were an opposing manager, would you rather face: Jarrod Washburn or Francisco Rodriguez? John Lackey or Brendan Donnelly? Tom Gordon or Jon Lieber? John Smoltz or Jaret Wright?

Take a look at how relievers and starters have matched up over the past 10 seasons:

           Starters               Bullpen             Difference
Year   AVG    OBP    SLG     AVG    OBP    SLG     AVG    OBP    SLG
1995  .270   .333   .423    .261   .338   .405   -.009   .005  -.018
1996  .274   .336   .435    .261   .339   .409   -.013   .003  -.026
1997  .268   .331   .425    .264   .339   .408   -.004   .008  -.017
1998  .271   .332   .430    .257   .331   .400   -.014  -.001  -.030
1999  .275   .341   .442    .263   .343   .417   -.012   .002  -.025
2000  .274   .341   .446    .264   .344   .418   -.010   .003  -.028
2001  .270   .331   .437    .252   .326   .405   -.018  -.005  -.032
2002  .266   .328   .427    .252   .328   .397   -.014   .000  -.030
2003  .268   .329   .432    .256   .330   .402   -.012   .001  -.030
2004  .270   .332   .438    .258   .331   .408   -.012  -.001  -.030

Bullpens have had a consistent and sizable advantage over starters in both AVG and SLG for ten years, but their Achilles' heel has been walks, a fault that has been dropping somewhat steadily recently. In 2004, relievers were better than starters in all three categories, not quite as dominant as 2001, but still consistently so.

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