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"Log-5" is a method introduced by Bill James to predict the probability of victory when two teams of a given winning percentage play against each other. The formula is:

WPct = A - ( A x B ) / (A + B) - ( 2 x A x B )

Where "A" is Team A's winning percentage, and "B" is Team B's winning percentage. In the simplest terms, this formula indicates how often Team A should beat Team B.

Imagine that Team A wins 50% of its games and Team B wins 38% of its games. Inputting these percentages (as a decimal) into the formula above would yield:

WPct = 0.31/ (0.88) - (0.38) = 0.62

Or, in other words, Team A should beat Team B 62% of the time.

Permanent link to Stat of the Week: Log-5

Leverage measures how important a given situation is during a game (relative to the start of the game). The start of a game is defined as a Leverage of 1.0, a neutral situation. As the game progresses, the Leverage can fluctuate based on the inning, the number of outs, the runners on base, and the difference between the two teams' runs scored so far.

Leverage is the ratio between how much a single run scored changes the expected probability of winning in the current situation and how much a run would have changed the expected probability of winning at the very beginning of the game.

For example, if a run scored in the eighth inning increases the probability of winning by 20%, while a run at the start of the game increases it by 10%, then the Leverage of the situation in the eighth inning is 20%/10% = 2.00 Leverage.

Permanent link to Stat of the Week: Leverage

Are Pitching Wins Important?

In the modern world of analytics and technology in the game of baseball new statistics are taking over! It seems new stats and formulas are implemented into baseball on a weekly basis, leaving older stats with less credibility. One stat in particular is the pitcher’s win and understanding the true meaning such a statistic holds. Let’s dive in!

APR, or Adjusted Pitching Runs, measures the number of runs a pitcher prevented as compared to a league-average pitcher in a neutral park in the same number of innings. Derived from the pitching component of linear weights, or pitching runs, APR includes an adjustment for ballparks and is based on all runs allowed, not just the earned runs.

APR = L x IP - (R/PF)

Where "L" is the league average of runs per inning and "PF" is the park factor for the pitcher's home park.

Permanent link to Stat of the Week: APR

RA, or Run Average, is the number of runs (earned and unearned) allowed by a pitcher or team per 9 innings. Considering all runs allowed by a pitcher is more desirable from a predictive standpoint because it adjusts the arbitrary format of official scoring and the attribution, the problems of reconstructing an inning to determine unearned runs, and the small number of errors presently compared to the past that would normally be seen when measuring pitcher success through just an "earned runs" method. A pitcher good at preventing earned runs tends to be good at preventing unearned runs.

Permanent link to Stat of the Week: RA

Credited to the Greek mathematician Pythagoras for describing the sides of a right triangle. Around the year 1980, Bill James, American baseball writer and statistician, discovered that you can tell how many games a team will win, based on its runs scored and runs allowed using a formula containing "three squares" like the pythagorean formula.

Pythagorean Record:

Winning % = (runs scored)^2 / [(runs scored)^2 + (runs allowed)^2]

The winning percentage is, of course, approximate and can be more accurate by adjusting the exponent. This adjustment is known as "Pythagenport", named after Clay Davenport who used logarithmic formulas to estimate the adjustment exponent based on runs scored and allowed. Later revisions to this method have been made.

Permanent link to Stat of the Week: Pythagorean Record

PSP is a measure designed by Nate Silver to indicate a team's success in the postseason in divisional play. PSP assigns points to playoff teams as follows:

  • 3 points for making the playoffs
  • 3 points for winning the League Division Series (LDS)
  • 4 points for winning the League Championship Series (LCS)
  • 4 points for winning the World Series
  • 1 point for each postseason win
  • -1 point for each postseason loss

The highest possible PSP is 25, for a team that sweeps through all eleven postseason games, while the lowest is 0, for a team that is swept in the first round.

Permanent link to Stat of the Week: Playoff Success Points (PSP)

MLV, or Marginal Lineup Value, is a statistic that measures a player's offensive production in runs above an average offensive player. MLV takes a theoretical team of nine average hitters, replaces one of them with a player we want to measure, gives him the same percentage of the team's total plate appearances (PA) as he had on his real team, and computes how many more (or fewer) runs the team would score as a result of the switch.

A positive MLV indicates that the player is an above-average hitter, and a negative MLV indicates the player is a below-average hitter. For example, a player with a 42.0 MLV means that the player would have produced 42 more runs for an average team than a league-average hitter would have had in the same amount of playing time. MLV is park-adjusted and calibrated to league average.

Permanent link to Stat of the Week: MLV

The sum of a player's on-base percentage (OBP) and their slugging average (SLG). This is a quick and easy statistic for understanding a player's offensive productivity.

OPS is more closely correlated to run scoring than batting average, on-base percentage, or slugging average alone, which is why many baseball fans prefer this statistic to compare players' offensive ability.

Understand that OPS has its limitations, such as the assumption that OBP and SLG are equal. For example, a player with a .340 OBP and a .340 SLG is offensively different than a player with a .440 OBP and a .240 SLG, despite each sets adding up to an OPS of .680.

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Permanent link to Stat of the Week: OPS

"Stress" is a way of characterizing how much of a pitcher's workload has been compressed into high pitch count outings. The higher the stress ratings over the course of a pitcher's career, the higher likelihood of arm injuries.

Stress = Pitcher Abuse Points(PAP)/# of Pitches

PAP = (# of Pitches -100)^3

According to Keith Woolner, starting pitchers who regularly work deeper into games decline in performance, as a group, after throwing a high number of pitches. In Baseball Prospectus 2001, he compared three weeks before and after pitchers' high-pitch outings and found that pitchers threw fewer innings per start, struck out fewer batters, and allowed more hits and walks in the subsequent starts.

Permanent link to Stat of the Week: Stress