CSS Button No Image Css3Menu.com

Baseball Prospectus home
  
  
Click here to log in Click here for forgotten password Click here to subscribe

Futures Guide 2014 is Now Available in Paperback and Three E-book Formats.

Premium and Super Premium Subscribers Get a 20% Discount at MLB.tv!

<< Previous Article
Premium Article Prospects Will Break Y... (11/15)
<< Previous Column
BP Unfiltered: Things ... (11/15)
Next Column >>
BP Unfiltered: Rereadi... (11/20)
Next Article >>
The Week In Quotes: No... (11/18)

November 18, 2013

BP Unfiltered

Rereading Nate Silver: 8. Converting the Pitcher

by Sam Miller


In which Nate Silver invents Three True Outcome Percentage right before our very eyes. In which Nate Silver provides us a way of ranking Vin Mazzaro ahead of Aroldis Chapman in something.

The Grand Experiment
March 12, 2003

Abstract: With two newsy examples as his hook, Nate looks at which types of pitcher have had disproportionate success converting from the bullpen to a rotation, and which types have struggled. Helpfully for his premise, Danny Graves and Byung-Hyun Kim (both, at the time, converting from the ninth inning to the first) were nothing alike. Graves was a finesser; Kim struck out a quarter of the batters he faced; Graves had a very moderate platoon split, Kim’s was giant. His findings: the pitchers who transitioned the best, relative to their talent level, were those who struck out few batters, walked few batters, and allowed few home runs.

Table 2: Correlations between RA Delta and peripheral statistics

        Strikeout rate:   -.46
        Walk rate:        -.20
        Home run rate:    -.39

The higher a pitcher ranked on a Three True Outcomes leaderboard, the better he was suited for the bullpen instead of the rotation.

Key Quote: "It's always easier to follow statistical evidence with intuition than the other way around, but this result, if it's real, makes plenty of sense. It simply isn't possible to pitch like Calvin Schiraldi for seven innings at a time; the pitch counts rise too quickly, and the strain on the arm is too great. A pitcher like Schiraldi needs to change his approach when pitching for extended stretches in a way that a pitcher like Billy Swift does not. Inevitably, that means allowing a few more runners to reach base. If the pitcher is also vulnerable to the long ball, as Schiraldi was, his RA can rise very quickly as solo shots turn into three-run jobs."

If It’s Real: If it’s real, we can apply it to the current crop of pitchers who are either going to convert or will be part of a convert-or-not-convert controversy. (And, as long as starters pitch three times as many innings, there will always be convert-or-not-convert controversies.) Did a quick poll of names to throw into the mix, and here they all are, sorted by TTO% as relievers over the past two seasons.

Pitcher Innings TTO%
Vin Mazzaro 91 23
Carlos Martinez 23.67 28
Robbie Ross 127.33 29
Justin Wilson 78.33 31
Alex Wood 21.67 34
Drew Smyly 80.33 35
Neftali Feliz 131.67 35
Aaron Crow 113 35
Joba Chamberlain 62.67 35
Dustin McGowan 25.67 35
Brett Cecil 71.67 36
Alex Torres 66 37
Trevor Rosenthal 98 42
Aroldis Chapman 135.33 56

(I went further back for Feliz. Some pitchers have only relieved for one inning.)

To be very clear: This isn’t saying Mazzaro would be a better starter than Rosenthal. Just that he would show the smallest delta between his relief work and his rotation work. That Rosenthal is more better in relief than Mazzaro is more better in relief. This, as a quick eyeballing of the list shows, is the central dilemma for teams: If Nate’s right, then the most benefit comes from converting the worst pitchers into the biggest roles. Which raises a whole secondary math problem.

But We Said IF It’s Real: Ben wrote about a group of convertees in spring 2012, and Colin Wyers’ research assistance turned up very different results.

Factor

Correlation

K Rate

.18

BB Rate

-.13

Age

.05

ISO

-.03

BABIP

.03

The walk rate was less helpful to a reliever converting to the rotation, but still helpful; the power rate was much less helpful, but still helpful; and the strikeout rate flipped entirely, from being a negative indicator for a relief pitcher to a positive indicator. By this prescription, Rosenthal likely flips to the best bet for converting.

Graves and Kim, incidentally, both flopped as starters.

Tables: 3
Graphs: 0
Equations: 0

On the Nate Silver Must-Read Scale: 1

Sam Miller is an author of Baseball Prospectus. 
Click here to see Sam's other articles. You can contact Sam by clicking here

0 comments have been left for this article.

<< Previous Article
Premium Article Prospects Will Break Y... (11/15)
<< Previous Column
BP Unfiltered: Things ... (11/15)
Next Column >>
BP Unfiltered: Rereadi... (11/20)
Next Article >>
The Week In Quotes: No... (11/18)

RECENTLY AT BASEBALL PROSPECTUS
Premium Article Painting the Black: Super Twoing
Premium Article What You Need to Know: Meltdown in Minnesota
Premium Article The Prospectus Hit List: Friday, April 18
Premium Article Notes from the Field: A-Ball Notes
Premium Article Raising Aces: Masahiro Tanaka, the Debut Ant...
Baseball Prospectus News: New Stat Reports a...
Premium Article Skewed Left: How Service Time Dictates Top P...

MORE FROM NOVEMBER 18, 2013
Premium Article Prospects Will Break Your Heart: Minnesota T...
Premium Article Baseball Therapy: Why Do Teams Overpay for F...
Premium Article Minor League Update: AFL Championship Game a...
Premium Article Rumor Roundup: Veteran Help Wanted
Fantasy Article Fantasy Team Preview: Minnesota Twins
The Week In Quotes: November 11-17

MORE BY SAM MILLER
2013-11-19 - Premium Article Pebble Hunting: The Hall of Fame 50 Percent ...
2013-11-19 - BP Daily Podcast: Effectively Wild Episode 3...
2013-11-18 - BP Daily Podcast: Effectively Wild Episode 3...
2013-11-18 - BP Unfiltered: Rereading Nate Silver: 8. Con...
2013-11-15 - Premium Article Transaction Analysis: What Do the A's Really...
2013-11-15 - BP Daily Podcast: Effectively Wild Episode 3...
2013-11-15 - BP Unfiltered: Weep, Mob, For the Downballot...
More...

MORE BP UNFILTERED
2013-11-25 - BP Unfiltered: Rereading Nate Silver: 11. Pa...
2013-11-21 - BP Unfiltered: Rereading Nate Silver: 10. On...
2013-11-20 - BP Unfiltered: Rereading Nate Silver: 9. Mag...
2013-11-18 - BP Unfiltered: Rereading Nate Silver: 8. Con...
2013-11-15 - BP Unfiltered: Things the Hall of Fame is No...
2013-11-15 - BP Unfiltered: Weep, Mob, For the Downballot...
2013-11-14 - BP Unfiltered: Rereading Nate Silver: 7. Day...
More...