Clubhouse Confidential serves as an open forum to discuss and debate the day's news and moves using modern statistical research and value projection. Don't understand the stats-speak? Check out the glossary of terms below. Catch up on highlights and interviews here.
BA: Batting Average ... (H/AB)
The rate at which a player gets a hit relative to his total at-bats. The average BA in the Majors for 2011 was .255.
BABIP: Batting Average on Balls in Play ... (H - HR)/(AB - K - HR + SF)
How many of a player's balls in play go for hits. BABIP removes HR, BB, and K -- outcomes not impacted by defense -- from the player's average. It can serve as a rough estimate of a player's luck, and can help predict future performance. The league rate stays around .300 (it was .295 in 2011). A higher BABIP often means a player is on the right side of luck (hits are falling in) and will regress. A lower number often implies a player is on the wrong side of luck and will improve. The metric can be used mostly for pitchers, and somewhat for hitters.
BB%: Walk Percentage ... (BB/PA)
How often a player walks relative to his total plate appearances. The average walk rate across MLB in 2011 was 8.1%. Jose Bautista walked at a rate of 20.2% in 2011; Yuniesky Betancourt, 2.7%.
BB/9: Walks Per 9 Innings Pitched ... (BB/IP)*9
How many batters a pitcher walks per nine innings. An excellent BB/9 is below 2. The average BB/9 across MLB in 2011 was 3.1. (Roy Halladay had a BB/9 of 1.35 for 2011.)
Ranking of positions by degree of difficulty from hardest to easiest: P, C, SS, 2B, CF, 3B, RF, LF, 1B, DH. Created by Bill James.
ERA: Earned Run Average ... 9 * (Earned Runs/IP)
The number of earned runs a pitcher allows per nine innings pitched -- it does not include runs which scored because of errors or passed balls. The average ERA across MLB in 2011 was 3.94.
ERA+: Adjusted ERA ... (LgERA/ERA) * 100
A pitcher's ERA relative to the league-average ERA and adjusted for his home ballpark. 100 is league average, below 100 would be below average; over 100 is above average. A 150 ERA+ means the pitcher's ERA is 50% better than a league-average pitcher.
FIP: Fielding Independent Pitching ... [(HR * 13) + (BB + HBP - IBB)*3 - (K * 2)]/IP
A single, ERA-like number, focusing on a pitcher's K rate, BB rate and HR rate (strikeouts, walks and home runs are not impacted by defense). By limiting its focus to factors a pitcher can control, FIP demonstrates a pitcher's effectiveness better than ERA. The average FIP across MLB in 2011 was 3.94.
xFIP: Expected Fielding Independent Pitching ... (FB * .106) * 13 + (BB + HBP - IBB) * 3 - (K * 2))/IP
Calculated much like FIP, but with the home run rate kept at the league-average rate of 10.6%. (Individual pitchers' home run rates often vary year to year.) The average xFIP in MLB for 2011 was 3.94.
FRS: Fielding Runs Saved
The measure of runs saved beyond what a league-average player at that position might have saved. The league average is 0.
JAWS: Jaffe WARP Score System
Assessment of a player's Hall of Fame worthiness using an average of their Peak WARP and total career WARP. Developed by Clubhouse Consultant Jay Jaffe.
K/9: Strikeouts Per 9 Innings Pitched ... (K/IP)*9
How many batters a pitcher strikes out per every 9 innings. An excellent K/9 is 9.0, or a batter an inning. The average K/9 across MLB in 2011 was 7.1.
K%: Strikeout Percentage ... K/PA
How often a batter strikes out relative to his total plate appearances. The average K% across MLB in 2011 was 18.6%. When Mark Reynolds set the single-season strikeout record in 2009 with 223 whiffs, his rate was 33.7%. Placido Polanco's career K% entering 2012 is 8.4%.
OBP: On Base Percentage ... (H + BB + HBP)/(AB + BB + HBP + SF)
The rate at which a player gets on base relative to his total plate appearances. (PAs include walks, hit-by-pitch, sacrifice hits and catcher interference; at-bats don't.) The average on-base percentage in MLB for 2011 was .321.
OPS: On Base Percentage Plus Slugging Percentage ... (OBP + SLG)
A single stat that estimates a player's offensive production. Note that in OPS, OBP and SLG are weighted evenly (they're summed), despite the two metrics being weighted differently themselves: OBP is calculated from plate appearances and SLG from at-bats.
OPS+: Adjusted OPS ... 100 * ( OBP/lgOBP + SLG/lgSLG - 1)/BPF
A batter's OPS relative to the league-average OPS and adjusted for his home ballpark. 100 is league average, anything below 100 is below average; over 100 is above average. Bautista held a 181 OPS+ in 2011, meaning his OPS was 81% better than a league-average hitter.
RC: Runs Created ... (TB * (H + BB)) / (AB + BB)
An estimation, developed by Bill James, of a player's offensive contribution to his team, measured in terms of runs. A precursor of wOBA (below).
SIERA: Skill-Interactive Earned Run Average
Estimates ERA through walk rate, strikeout rate and ground ball rate, eliminating the effects of park, defense and luck. Developed by Baseball Prospectus.
SLG: Slugging Percentage ... ((1B) + (2 * 2B) + (3 * 3B) + (4 * HR))/AB
The rate at which a player gains total bases relative to his total at-bats. The average slugging percentage in MLB for 2011 was .399.
TAv: True Average
Formerly known as Equivalent Average, TAv, developed by Baseball Prospectus, is an expression of how many runs a player created per plate appearance, translated to a batting average-like number. The average TAv in the Majors is .260.
UZR: Ultimate Zone Rating
How many runs above or below average a player was worth defensively. 0.0 is considered average. Developed by Mitchel Lichtman.
WAR: Wins Above Replacement
A single statistic summarizing a player's offensive and defensive contributions. WAR calculates the amount of wins a player adds to his team compared to the contribution that would be expected from a replacement-level player. A replacement-level player is a player who can be signed for mimimum cost, i.e. someone on the waiver wire or a Minor League free agent. 0.0 WAR over a season denotes a replacement-level player, 2.0 is a regular starter, 5.0 is All-Star worthy and a WAR of 8 or above means the player is worthy of MVP consideration.
fWAR: Fangraph.com's WAR calculation, which includes FIP for pitchers, and UZR for defense (see above)
rWAR: Baseball-Reference.com's WAR calculation, which includes defensive runs saved (plus-minus) when calculating pitching, TotalZone for defense, and baserunning
WARP: Wins above replacement player according to Baseball Prospectus
WHIP: Walks and Hits Per Innings Pitched ... (W + H)/IP
The number of walks and hits allowed by a pitcher per inning. Essentially, this equals baserunners per inning. A WHIP of 1 or below is considered elite. The average WHIP across MLB in 2011 was 1.32.
wOBA: Weighted On Base Average
A single stat that takes into account how a player gets on base, not just that a player gets on base, by assigning more value to extra-base hits. wOBA weighs each aspect of hitting in proportion to its run value, unlike OPS. The average wOBA across MLB in 2011 was .316.
WPA: Win Probability Added
A calculation of how a player affects his team's win expectancy from play to play, over the course of a game. For example, a player who homers in a late-and-close situation will have a higher WPA than one who strikes out.
Computer-based offensive player projection system, not allocated to predicted playing time, developed by Daniel Szymborski of Baseball Think Factory. ZiPS pitching predictions are based on the AL having a 4.19 ERA and the NL having a 3.96 ERA.