Ajusted ERA+

Vol. 3

Pedro Martinez

Pedro in 1999 (Ezra O. Shaw/Getty Images).

This week, TWIB looks at the ever expanding global presence in the game
by taking viewers inside two of baseball’s newest frontiers: China and
Colombia. While Asian countries like South Korea and Japan have
embraced the game for decades, China is getting a crash course intro to
baseball – they participated in the first World Baseball Classic, and
will compete in the 2008 Summer Olympics. Furthering this progress, MLB
held an exhibition series there this offseason with the Dodgers and the
Padres, and TWIB was there covering all the action. And while Latin
American countries have been pumping out MLB talent like model-T Fords,
surprisingly only seven MLB players have ever called Colombia their
place of birth. Among the seven is Orlando Cabrera, and he’s doing his
part to raise that number by working with his own baseball club in the
offseason. Once again, TWIB tagged along, capturing stuff you won’t see
anywhere else. Hopefully you’ll enjoy those two pieces this week.

To coincide with this global theme on TWIB, naturally I want to
talk to you about a stat called adjusted ERA+. What, you don’t see the
connection? Don’t worry, I’ll get you there, and give you a little
adjusted ERA+ 101 in the process. But first, have you tried to compare
pitchers like Tom Seaver to Greg Maddux, or Sandy Koufax to Lefty
Grove, and were told you can’t compare pitchers from different eras?
Well you can, sort of, with the help of adjusted ERA+, a stat that
attempts to reveal how a pitcher performs compared to the rest of his

According to www.baseball-reference.com,
adjusted ERA+, or *ERA+ for short, is the ratio of the league’s ERA,
factoring in the effect of the pitcher’s ballpark (the adjusted part)
to that of the pitcher. A score over 100 indicates the pitcher
performed above average and a score less than 100 means the pitcher
performed below average. For instance, if Pittsburgh Pirate pitcher A
posts a 4.35 ERA and the league ERA in PNC Park is 4.35 (which it was
in 2007), his *ERA+ would be 100, meaning that he pitched at the league
average for 2007 in PNC Park. Paul Maholm posted a 5.02 ERA in 2007,
putting his *ERA+ at 87, making him a below league average pitcher. Ian
Snell had a 3.76 ERA, giving him a 116 *ERA+, indicating he pitched
above the league average.

Adjusting the league ERA for ballpark factor is important because of
how much of an impact stadiums can have on scoring. An easy example is
Coors Field, which is widely regarded as a hitter’s park. So when Aaron
Cook posted a 4.12 ERA, it gave him an *ERA+ of 116 (the same as Ian
Snell) because the ERA of Coors Field was 4.79.

*ERA+ can be compiled for any pitcher from any season in
history, giving us a wealth of information to have some fun with. Most
people look at Bob Gibson’s 1968 ERA of 1.12 as the benchmark for
pitching excellence, but how much is his *ERA+ affected by the pitching
dominant 1968 season? Even though the adjusted league ERA for Gibson in
1968 was 2.90, his 1.12 ERA gave him an amazing ERA+ score of 258, good
for 7th on the all-time single season list. However it might surprise
you to know that right ahead of him on that list with an *ERA+ of 259
is Walter Johnson, whose 1.14 ERA in 1913 rates a little better because
his league average ERA was 2.96.

*ERA+ is also gathered for career totals, so back to the
debates: who was better, Tom Seaver or Greg Maddux; Koufax or Grove?
We’ll never know for sure, but at least now we can know who pitched
better in relation to his league – Seaver posted a career *ERA+ of 127
while Maddux currently has an ERA+ of 134. Koufax posted a career 131
*ERA+, but Lefty Grove has the 2nd highest career ERA+ with 148, which
finally leads into why we’re talking about this in conjunction with a
global game theme show. The all-time *ERA+ leader is Dominican born
Pedro Martinez, with a career mark of 160. Pedro also owns the highest
*ERA+ for a single season with a staggering 291 in 2000, indicating his
1.74 ERA was nearly three times better than the adjusted league average
of 5.07. In fact, Pedro topped the 200 *ERA+ level a record five times
in his career. So let’s have three cheers for Pedro Martinez, the most
dominant pitcher in baseball history, courtesy of the Dominican

Before we get too excited, *ERA+ is not all encompassing.
First, it measures an average, which doesn’t take into account
longevity and how many innings you’ve thrown. Because of this, the
career *ERA+ list is flooded with relievers. Also, the measurement
isn’t exact, as it roughly adjusts for the ballpark factor, which
itself is sometimes questioned for its accuracy. And like any other
stat, it only lets you know how a player performed in his own
environment. So while we can’t say Pedro Martinez is the greatest
pitcher of all time with any concrete evidence, we can say he dominated
his league like nobody before or since. Regardless, have some fun with
the power of comparing history’s greatest pitchers with a single
number. And by the way, you can do the same things with hitters, using

The Top 10 career *ERA+ scores for starting pitchers, minimum 2000 IP:

1. Pedro Martinez – 160
2. Lefty Grove – 148
3. Walter Johnson – 147
4. Ed Walsh – 146
5. Roger Clemens – 143
6. Addie Joss – 142
7. Al Spaulding – 142
8. Kid Nichols – 140
9. Randy Johnson – 139
10. Cy Young and Three Finger Brown – 138

For a more detailed description of *ERA+ and the actual formula, you could look it up at: http://www.baseball-stats-online.com/bbso/glossary/pglossary.html

Triple Crown TWIBia #2 answers

Last week, hoped you guessed it, I was paying homage our show’s subject, the Phillies.

1) .386 AVG, 40 HR, 170 RBI – Chuck Klein, OF, 1930
2) .407 AVG, 13 HR, 141 RBI – Sam Thompson, OF, 1894
3) .316 AVG, 31 HR, 91 RBI – Mike Schmidt, 3B, 1981
4) .272 AVG, 28 HR, 100 RBI – Juan Samuel, 2B, 1987
5) .317 AVG, 40 HR, 110 RBI – Dick Allen, 3B, 1966

At press time, Greg Holcombe was our lone 5 for 5 contestant from last week. He’s now 15 for 15 overall.

Triple Crown TWIBia #3

Let’s do some pitching triple crown stats, which are wins, ERA,
and strikeouts. I’m listing the pitcher’s win-loss records, because for
me they go hand in hand in defining a season. And with all of these, I
hope you take the time to fish around for the answers; hit the books or
the websites. There’s no cheating here, it’s just an exercise in
learning about baseball’s glorious past and present. My favorite
resource is www.baseball-reference.com

1) 24 – 4, 1.53 ERA, 268 strikeouts
2) 34 – 5, 1.91 ERA, 258 strikeouts
3) 26 – 9, 1.94 ERA, 275 strikeouts
4) 25 – 3, 1.74 ERA, 248 strikeouts
5) 24 – 8, 1.82 ERA, 301 strikeouts
6) 25 – 6, 2.23 ERA, 222 strikeouts
7) 18 – 6, 1.74 ERA, 284 strikeouts
8) 28 – 12, 1.53 ERA, 150 strikeouts
9) 23 – 12, 1.75 ERA, 170 strikeouts
10) 6 – 1, 2.48 ERA, 43 strikeouts

To return to the twib main page: twib.mlb.com

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