What's better than ERA to measure a pitcher’s effectiveness?
June 5, 2008
For hitters, for years and years,
it was batting average that was thought to be the
best single statistic to look at to evaluate a
hitter. In the last couple of decades, the
weaknesses of batting average have been exposed and
the value of getting on base and hitting for power
have become better recognized. The stat that is
becoming the new standard for hitters is OPS—On-base
percentage Plus Slugging percentage.
For pitchers, the standard is ERA.
Compared to batting average, it provides a much
better representation of effectiveness. It measures
the most important quality of a pitcher's job,
preventing runs. However, it too has its flaws. The
biggest flaw is that a pitcher's ERA can be greatly
affected by the pitchers that immediately follow him
in a game, both positively and negatively.
Enter Opponent OPS. This is a
stat that you hardly ever see. It makes just as much
sense to look at Opponent OPS for pitchers as it does
to look at a hitter's own OPS. We just recently
added this as a leaderboard titled "Opponent OPS" to
Bill James Online and I wanted to
share it with you.
ERA is going to continue to be the
standard, and I will personally look at ERA for every
pitcher, but I think Opponent OPS may be a better
indicator of a pitcher's overall effectiveness. In
fact, in a way, we've been suggesting this for quite
a while as we've published component ERA in the Bill James Handbook.
Component ERA is, in essence, a restated Opponent OPS
since it is based on nearly the exact same components
that go into OPS, namely hits, home runs, walks
allowed, and hit batsmen. Opponent OPS adds in
doubles and triples allowed as part of the
equation.
Here are the Opponent OPS leaders
thus far this year:
|
Opponent OPS—2008 |
| Player
|
OPS |
ERA |
| Ryan Dempster,
Cubs |
.561 |
2.75 |
| Edinson Volquez,
Reds |
.563
|
1.32 |
| Brandon Webb,
Diamondbacks |
.567
|
2.69 |
| Shaun Marcum,
Blue Jays |
.568
|
2.63 |
| Jose Contreras,
White Sox |
.570
|
2.89 |
| Ervin Santana,
Angels |
.592
|
3.02 |
| Cliff Lee, Indians
|
.603
|
2.45 |
| Roy Halladay,
Blue Jays |
.609 |
2.94 |
| Joe Saunders,
Angels |
.614
|
2.63 |
| Tim Lincecum,
Giants |
.624
|
2.23 |
The number one guy so far this
year is a surprise, the Cubs' Ryan Dempster. Dempster
struggled as a starter and did well as a reliever
earlier in his career. Now he is turning it around
and doing great as a starter after having some relief
problems late last year.
