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It's funny. Dr. D can work hard on a Sizzler and Fizzler, which engages the Seattle Mariners, and Denizens nod politely and move on. : ) Or he can swing by a Bill James column for 15 minutes' work, tag on a couple M's at the end, and get 30 comments in a breeze. I guess the Think Tank is sabermetric at heart. No, I'm kidding of course; James' columns usually have a fresh idea to work with.
His latest is "Pitching and the Persistence of Excellence." It's a monster article, 3,000 words it looks like, and he's attacking this question he had. James once said he is always thinking about baseball, even dreaming about it, and the only way he's not thinking about it is "if I'm in a movie, but it has to be a really good movie." Here, he wanted to know, What is Masahiro Tanaka's chance of being an excellent pitcher THIS year? He says
The exact two questions we are asking are:
1) If a pitcher is excellent in one season, what are the odds that he will be excellent again in the next season, and
2) How does this vary with various inputs?
But before we get to those, we have to start with questions like "What are we going to define as an excellent pitcher?"
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In terms of designing his study, he starts off like this:
It also happens that these two measurements (ERA and runs saved  Dr D) tend often to be about the same, for the very best pitchers. I used three figures to define the list: M1, M2 and M3.
M1 is the pitcher’s ERA, divided by the league ERA, subtracted from 1.00, multiplied by 100.
M2 is the number of earned runs a leagueaverage pitcher would have allowed in the number of innings pitched by this pitcher, minus the number of runs that this pitcher did allow.
M3 is the minimum of M1 and M2.
My study group was "all pitchers who recorded at least one out in a season from 1920 to 2015"
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Then, you know him, he tweaks and tweaks until he gets better and better results. But check out what he settles on at the end of the novella!
OK, then; our "Excellence Repeat Predictor" is:
The pitchers strikeouts minus his walks, per nine innings,
Minus the league average of the same,
Times 6,
Plus the number of runs the pitcher has saved compared to a leagueaverage pitcher, as measured by ERA.
In all of baseball history, the ten pitchers most likely to repeat as excellent were:
First

Last

Year

Pedro

Martinez

2000

Pedro

Martinez

1999

Randy

Johnson

2001

Randy

Johnson

1999

Randy

Johnson

2002

Randy

Johnson

2000

Pedro

Martinez

2002

Pedro

Martinez

2003

Lefty

Grove

1931

Mariano

Rivera

2008

All ten of them did in fact repeat as excellent, except for Randy Johnson in 2002.
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This really took me aback. After 9,000 sophisticated measurements, which  > are trying to predict an SP's season this year? The best you have is simply K/BB plus IP.
Think about that for a second.
....
TAKEAWAY 1  the best way to predict a great season for an SP is simply K/BB. And durability. Like James told me 20 years ago, when looking at pitchers he simply starts with the K/BB ratio, and then looks for something out of alignment in the stats (like gopheritis or GB ratio being weird).
If you're a casual reader, that's a great takeaway. For all of Baseball Prospectus' work? You can do just about as well by looking at K and BB.
....
TAKEAWAY 2  If you're not a paid subscriber ($3/mo) then you would not BELIEVE how LOW every pitcher's chance is of repeating. Here are the Astros:






ASTROS

Name

IP

ER

SO

BB

ERA

Estimate

Verlander,Justin

206.0

77

219

72

3.36

50%

Morton,Charlie

146.7

59

163

50

3.62

38%

Keuchel,Dallas

145.7

47

125

47

2.90

35%

Peacock,Brad

132.0

44

161

57

3.00

53%

Devenski,Chris

80.7

24

100

26

2.68

57%

Giles,Ken

62.7

16

83

21

2.30

61%








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Dallas Keuchel has a 35% chance of an excellent season? (He defines "excellent" as merely a 110 ERA+ and 7 total runs saved.)
....
Finally, here are the Mariners. By the way, 20% is the chance a random SP has of an excellent season.






MARINERS

Name

IP

ER

SO

BB

ERA

Estimate

Leake,Mike

186.0

81

130

37

3.92

20%

Paxton,James

136.0

45

156

37

2.98

62%

Diaz,Edwin

66.0

24

89

32

3.27

40%

Vincent,Nick

64.7

23

50

13

3.20

22%

Zych,Tony

40.7

12

35

21

2.66

16%








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Paxton's 62% is one of the highest in baseball, despite his low innings pitched, ergo low "total runs saved."
TAKEAWAY 3  Paxton's lack of durability in 2017 matters much less in 2018, than the fact that he is so incredibly great. If you want to draft a winner, go for the Ferrari instead of the Honda.
Tolja : )
TAKEAWAY 4  It would be interesting to know, "How much does the figure go up, after Paxton throws a couple of great games in 2018?" I'll bet the impact would be pretty heavy on the odds. Paxton's next game, or two, or three, will cement* him for 2018, or not, I'd say.
.....
Mike Leake's 20% chance is the same as a random starter, per James. That's not an insult. There are 75 starters in the American League and the #38 starter isn't chopped liver. It's just that you better have 89 starters who give you a chance to win. Andrew Moore is gonna get his shot this year. Hope Rob Whalen does too.
.....
Felix isn't on there; I honestly don't know that it's because his estimate is 3% or something. Remember his K/BB was good last year, 78:26, but he only pitched 86 innings. Maybe the total runs saved nixed him.
.....
MarcO is, strictly speaking, only a prospect. Although he's a prospect this close :: fingers an inch apart :: to Best Bet status : )
Enjoy,
Dr D
*every pitcher can go on the DL. Every year.
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