LI (leverage index): A measure of how important a particular situation is in a baseball game depending on the inning, score, outs, and number of players on base, created by Tom Tango.

Baselines: The average LI is 1 and is considered a neutral situation. 10% of all real game situations have a LI greater than 2, while 60% have a LI less than 1.

Why you should care: Because LI puts a single number on the importance of a situation, it creates a much simpler and specific way of determining which situations in games are important. It can also be applied to players. See below for various LI player stats:

pLI: A player’s average LI for all game events.
phLI: A batter’s average LI in only pinch hit events.
gmLI: A pitcher’s average LI when he enters the game.
inLI: A pitcher’s average LI at the start of each inning.
exLI: A pitcher’s average LI when exiting the game.

See Critical Situations: Part 3 for more details

Additional Links and Resources:

Critical Situations Part 1, Part 2, Part 3
Leverage Index Tables

The leaderboards are up for Pitch Type & Velocity! There are a couple standard leaderboard functions that do not work with the Pitch Type tab.

-Starters and Relievers cannot be broken down yet.
-You cannot filter by league.
-You can select the minimum IPs.
-You can select only qualified players.

If there’s a % sign in the column, it’s the percentage of pitches thrown and if there’s a “v” after the pitch type, it’s the average velocity of the pitch.

Quick refresher on what means what: FB – Fastball, SL – Slider, CT – Cutter, CB -Curveball, CH- Changeup, SF – Split-fingered Fastball, KN – Knuckleball, XX – Unidentified, PO – Pickoff Attempt

RC (runs created): An estimator of how many runs a batter produces for his team, created by Bill James.

“Basic”: ((H + BB) * (1B + (2*2B) + (3*3B) + (4*HR))) / (AB + BB)

“Technical”: ((H + BB – CS + HBP – GDP) * ((1B + (2*2B) + (3*3B) + (4*HR) + (.26 * (BB – IBB + HBP)) + (.52 * (SH + SF + SB)))))/ (AB + BB + HBP + SF + SH)

Which formula and when: FanGraphs employs both formulas depending on what stats are available for individual seasons. Seasons prior to 1955 use the “Basic” formula and any season after and including 1955 uses the “Technical” formula.

Why you should care: Runs Created is a good estimator of how many runs a team should have scored in a given season. When applied to players, it is somewhat less accurate though still a useful estimator of a player’s actual production.

Variations: There are other run estimators that do a better job then Runs Created, yet one of the main advantage of Runs Created is that it’s extremely easy to calculate. Other run estimators include: Batting Runs, Base Runs, Extrapolated Runs, Estimated Runs Produced, Equivalent Runs.

Links and Resources:

Wikipedia: Runs Created
A Brief History of Run Estimation: Runs Created
How Runs are Really Created Part 1, Part 2, Part 3
The Book Wiki: Runs Created
The Book Wiki: Run Estimators

RE24 (runs above average by the 24 base/out states): RE24 is the difference in run expectancy (RE) between the start of the play and the end of the play. That difference is then credited/debited to the batter and the pitcher. Over the course of the season, each players’ RE24 for individual plays is added up to get his season total RE24.

Calculation Example: In game 4 of the 2007 World Series, the RE for the Red Sox to start the inning was .52. When Jacoby Ellsbury doubled off Aaron Cook in the very first at-bat in the game, the Red Sox were then expected to score 1.15 runs for the rest of the inning. The difference or RE24 was .63 runs. Ellsbury was credited +.63 runs and Aaron Cook credited with -.63 runs.

Why you should care: RE24 tells you how many runs a player contributed to his team. It’s similar to WPA (except in runs), but unlike WPA it does not take into account the inning or score of the game. Therefore, it is a more context neutral statistic. It does however take into account how many runners are on base and how many outs are left in the inning.

Variations: REW (run expectancy wins) is RE24 converted to wins.

Links and Resources:

Run Expectancy by Run Environment
The Book Wiki: Run Expectancy

I put up something new today which I think is very cool. Under each pitcher page, in the very bottom table, you can now see the percentage of each type of pitch a player threw and its average velocity. These stats are available from 2005-2007 and will be updated daily when the season starts.

Some quick things to note:

-The average velocity is in parenthesis next to the % of the pitch thrown.

-The percent of any known pitch type is a percentage of only known pitch types thrown. XX is an unidentified pitch type and is taken as a percentage of all pitches thrown.

-PO are pickoff attempts and are calculated as a percentage of all pitches thrown.

A huge thanks goes out to Baseball Info Solutions for allowing me to do this. This is a work in progress and there’s more that can be done with stats like these so feel free to chime in with suggestions.

Update: I’ve removed SW (Screwball), FO (Forkball), and SI (Sinker) and moved them into SF (Split-fingered Fastball). There were just so few pitches categorized as those three, it didn’t make sense for them to have their own bucket.

FB: Fastball, CT: Cutter, CB: Curveball, SL: Slider, CH: Changeup, SF: Split-fingered Fastball, KN: Knuckleball, XX: Unidentified, PO: Pickoff Attempt

WPA (win probability added): WPA is the difference in win expectancy (WE) between the start of the play and the end of the play. That difference is then credited/debited to the batter and the pitcher. Over the course of the season, each players’ WPA for individual plays is added up to get his season total WPA.

Calculation Example: In game 4 of the 2007 World Series, the WE for the Rockies started out at 50%. When Jacoby Ellsbury doubled off Aaron Cook in the very first at-bat in the game, the Rockies WE declined to 44.2%. The difference or WPA was .058 wins (5.8%). Ellsbury was credited +.058 wins and Aaron Cook credited with -.058 wins.

Why you should care: WPA takes into account the importance of each situation in the game. A walk off home run is going to be weighted more than a home run in a game that has already gotten out of hand. This makes it a great tool for determining how valuable a player was to his team’s win total.

When not to use it: WPA is more of a descriptive statistic and not that great of a predictive statistic. There are better statistics to use in raw player evaluations than WPA.

Links and Resources:

The Hardball Times: The One About Win Probability
The Book Wiki: Win Probability Added
Wikipedia: Win Probability Added
WPA is… WPA is not…

K/9 (strikeouts per 9 innings): The average of how many batters a pitcher strikes out per 9 innings pitched.

Calculated as: (SO * 9) / IP

Why you should care: K/9 is a perfectly suitable way to evaluate a player’s ability to strike batters out.

Current Baselines (2002-2007): The average K/9 for starting pitchers is 6.17 and 7.21 for relievers. For starting pitchers the top and bottom 20th percentile are a K/9 above 7.56 and below 4.89. Relievers top and bottom 20th percentiles are a K/9 above 8.94 and below 5.54.

Variations: Some people prefer to use strikeouts per batter faced (K% or K/G) to express a player’s ability to strike batters out. The difference is minimal and the argument for using K% is that K/9 excludes walked batters and K% does not, suggesting that K/9 may either overstate or understate a pitcher’s overall effectiveness (not pure strikeout ability).

Links and Resources:

Wikipedia: Strikeouts per 9 innings pitched
U.S.S. Mariner: Evaluating Pitcher Talent

Because the FanGraphs glossary sucks so much, I’ve decided to update the glossary by posting one article each day on a particular statistic.

They’ll be easily accessible through the blog and eventually the glossary tab once all the stats are completed. Until then the old glossary will remain intact. Overall, I’m trying to make them fairly thorough, but feel free to comment and add new links and information if you feel what I post is incomplete or inadequate.

Just as the title says, they’ve been updated to the latest and greatest. There are a few players not in the database yet and here are their projections:

Alexei Ramirez: .282/.347/.455 (220 AB)
Kosuke Fukudome .289/.368/.476 (557 AB)

Hiroki Kuroda: 10-10, 0 SV, 175 IP, 115/52 K/BB, 4.01 ERA
Kazuo Fukumori: 3-4, 2 SV, 60 IP, 41/35 K/BB, 5.25 ERA
Masa Kobayashi: 4-4, 0 SV, 68 IP, 50/19 K/BB, 4.24 ERA
Yasuhiko Yabuta: 4-4, 0 SV, 75 IP, 61/28 K/BB, 4.08 ERA

Jeff Sackmann of MinorLeagueSplits.com fame created his own set of projections for use in John Burnson’s Graphical Player 2008. He was kind enough to offer them for use on FanGraphs and now they’re available in the player pages and in their own sortable stats page.

His MINER projections are based off of the Marcel projections, but take into account batted ball data and minor league stats, including minor league batted ball data.

Still working on getting a link for a downloadable spreadsheet of the projections, but that should soon be available for those of you who want to play with them.