TRA (baseball statistic)
Encyclopedia
tRA is a baseball statistic used to measure the performance of a pitcher. Similar to FIP
, tRA uses a mathematical formula to isolate the pitcher from his defense. Thus, tRA is a defense-independent pitching statistic
. Unlike FIP and dERA
, however, tRA takes into account batted ball type (that is, line drives, fly balls, pop ups, and ground balls) as well as strikeouts, walks, and home runs.
tRA uses play-by-play data gathered from each MLB
season in order to give each possible outcome between a pitcher and a batter a linear weight. For example, in 2008, a line drive went for an out 30.5% of the time, while it had a run value of 0.384. These statistics are used to calculate expected outs (xOuts) and expected runs (xRuns). Once these values are obtained, tRA can be converted to runs per nine innings by taking (xRuns/xOuts)*27.
Like other sabermetrics, tRA has alternate versions. tRA+ is compared to league average. For example, a tRA+ of 120 would mean that pitcher was 20% better than league average. tERA is tRA except that it is scaled to earned runs
allowed instead of runs allowed
.
Defense independent pitching statistics
In baseball, defense-independent pitching statistics measure a pitcher's effectiveness based only on plays that do not involve fielders: home runs allowed, strikeouts, hit batters, walks, and, more recently, fly ball percentage, ground ball percentage, and line drive percentage...
, tRA uses a mathematical formula to isolate the pitcher from his defense. Thus, tRA is a defense-independent pitching statistic
Defense independent pitching statistics
In baseball, defense-independent pitching statistics measure a pitcher's effectiveness based only on plays that do not involve fielders: home runs allowed, strikeouts, hit batters, walks, and, more recently, fly ball percentage, ground ball percentage, and line drive percentage...
. Unlike FIP and dERA
Defense-Independent ERA
In baseball statistics,Defense-Independent ERA , created by Voros McCracken, projects what a pitcher's earned run average would have been, if not for the effects of defense and luck on the actual games in which he pitched.-Method:...
, however, tRA takes into account batted ball type (that is, line drives, fly balls, pop ups, and ground balls) as well as strikeouts, walks, and home runs.
Theory and method
tRA was developed by Graham MacAree. According to StatCorner, "The batter may strike out looking, strike out swinging, walk, be walked intentionally or be hit by a pitch. The hitter may also hit a line drive, a ground ball, an outfield fly, a popup, a bunt or a home run. These possibilities can be regarded as being governed by the pitcher, provided that there is a large enough sample size. tRA is built around knowing how many runs and outs each of these events are worth."tRA uses play-by-play data gathered from each MLB
Major League Baseball
Major League Baseball is the highest level of professional baseball in the United States and Canada, consisting of teams that play in the National League and the American League...
season in order to give each possible outcome between a pitcher and a batter a linear weight. For example, in 2008, a line drive went for an out 30.5% of the time, while it had a run value of 0.384. These statistics are used to calculate expected outs (xOuts) and expected runs (xRuns). Once these values are obtained, tRA can be converted to runs per nine innings by taking (xRuns/xOuts)*27.
Like other sabermetrics, tRA has alternate versions. tRA+ is compared to league average. For example, a tRA+ of 120 would mean that pitcher was 20% better than league average. tERA is tRA except that it is scaled to earned runs
Earned run
In baseball, an earned run is any run for which the pitcher is held accountable . Any runner who tags his base and reaches home plate is scored against the pitcher as an earned run...
allowed instead of runs allowed
Runs per nine innings
In baseball statistics, runs per nine innings is a measure of a pitcher's effectiveness in preventing runs; calculated as: / ....
.