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Tagbaseball facts

"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

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

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

Batting average is a measure of a hitter's performance, and is calculated by dividing a player's hits by their total at-bats, over a period of time. Batting averages can range from .000 (NO hits in all at-bats) and 1.000 (a hit in EVERY at-bat). In the absence of walks, reaching a base on errors, or being hit by a pitch, a hitter with a .300 batting average gets a hit 30% of the time they come to the plate. Take any batting average (.350, .105, .446) and multiply it by 100 to get the statistic as a percentage (35%, 10.5%, 44.6%).

The MLB average batting average for the 2019 season was .252, and the batting average leader of the 2019 season was Tim Anderson of the Chicago White Sox; .335 in 498 at-bats (AB).

Permanent link to Stat of the Week: Batting Average (AVG or BA)

Last week, we discussed what a Hit was. It is crucial to understand this before we dive into these conditions, as each condition is a type of hit.

A single (1B) or base hit occurs when the batter hits the ball into play and reaches 1st base safely. In order for a batter to be credited with a double (2B), the batter (now a "baserunner") must reach 1st base safely and then 2nd base safely. In order for a batter to be credited with a triple (3B) (you guessed it) they must reach 3rd base safely after touching 1st base and 2nd base.

A home run (HR) exists in two conditions:

  1. The batter hits the ball over the outfield wall in "fair territory"(area in-between the two foul poles in left and right field).
  2. The batter hits the ball into play and the runner advances all the way to home plate safely.

It is important to note that the baserunner must touch every base they're attempting to reach while the ball is in play. If they fail to do so, they must go back to that base (in reverse order), touch it, then continue to advance. If a defensive player in possession of the ball beats the runner there, the runner will be called out.

The baserunner will not be credited with any of these conditions if they reached any of these bases on an error or fielder's choice. If the baserunner attempts to reach 2nd, 3rd, or home plate after touching 1st base, but is called out at any of those bases by an umpire, the baserunner will still be credited with a hit in the official scorebook.

Permanent link to Stat of the Week: Singles (1B), Doubles (2B), Triples (3B), & Home Runs (HR)

In baseball, a "hit" is simply a condition in which the batter hits the ball into play and (at least) reaches 1st base safely.

"Safely" means the batter reached a base without being tagged with the ball first or beat to the base by a defensive player in possession of the ball, or reached the base because the ball wasn't caught before it touched the ground. In order to be ruled as a hit, the batter CANNOT reach the base on an error or a fielder's choice.

Permanent link to Stat of the Week: Hit (H)