Quality Start and Pitcher Usage Interpreter
Quality Start and Pitcher Usage Interpreter
A quality start is six or more complete innings with three or fewer earned runs — coined by a newspaper writer in 1985 and defined in no rulebook. Its standing objection is arithmetic: the minimum qualifying outing is an earned run average of 4.50, and the definition cannot tell it apart from a shutout.
Does this start qualify?
Six innings, three earned runsSix complete innings and no further outs, three earned runs, no decision
The definition, and the rate each outing actually implies
| Innings | Earned runs | Earned run average for the outing | Quality start? |
|---|---|---|---|
| 6 | 3 | 4.50 | yes — the minimum |
| 6 | 0 | 0.00 | yes |
| 8 | 3 | 3.38 | yes |
| 9 | 4 | 4.00 | no |
| 7 | 4 | 5.14 | no |
| 5 innings and 2 outs | 0 | 0.00 | no |
Three labels from one writer, and which of them MLB’s glossary carries
| Label | What it means | Published by MLB? | In any rulebook? |
|---|---|---|---|
| Quality start | at least six complete innings and no more than three earned runs | yes, with a glossary entry of its own | no |
| Tough loss | a quality start that the pitcher lost | yes — the same entry credits Lowe with the term | no |
| Cheap win | a win in a start that was not a quality start | yes — the same entry | no |
| Win and loss | the official scorer’s decision on the game | yes | yes, in the Official Baseball Rules |
What this page decides and what it cannot
| Here | Elsewhere | |
|---|---|---|
| Apply the quality-start definition to one start | yes | — |
| Name a start a tough loss or a cheap win | yes, from the decision field | — |
| Compute the earned run average the outing implies | no — the table above works six of them out | the earned run average calculator on this site |
| Say how much better the average quality start is than the minimum | no — nothing read for this page gives a figure | nowhere this author could reach |
| Decide whether a run was earned | no, and no arithmetic can | the official scorer at the ground, under Rule 9.16 |
| Apply the definition to a seven-inning competition | no — the threshold was written for nine | no seven-inning version was found anywhere |
Two thresholds standing in for a rate, invented in 1985 and carried by no rulebook
A quality start is one of the shortest definitions in baseball: six or more innings with three or fewer earned runs. MLB’s glossary gives it as “A starting pitcher records a quality start when he pitches at least six innings and allows three earned runs or fewer”, and SABR gives it identically as “a start lasting six or more innings with three or fewer earned runs allowed”. Both credit John Lowe of the Philadelphia Inquirer with coining it, MLB’s glossary in 1985 and SABR in December of that year, and MLB’s entry credits him with the two companion labels as well — the tough loss and the cheap win, for the starts whose result disagrees with them.
Major League Baseball publishes this figure in its own statistics glossary, and the Official Baseball Rules do not define it: Rule 9.21 is the list of percentages the rulebook defines, and this is not one of them. That is not a reason to distrust the arithmetic, which is universal in published records. It is the reason the definition here is quoted from a glossary entry, and the reason the rule numbers that do appear on this page belong to something other than the headline — a quantity it is built from, or a statistic printed beside it for comparison — rather than to the headline itself.
The objection to it is arithmetic, and it is quoted here rather than paraphrased. SABR prints it as a reader would say it: “Three runs in six innings? That’s a 4.50 ERA! In what world is that a measure of quality?” Nobody disputes the sum. Three earned runs over six innings is three times nine divided by six, which is 4.50, and that is the FLOOR of the definition — the worst outing it admits. Worse still, the definition is a pair of thresholds rather than a rate, so it can order two starts the opposite way from the rate both of them imply: nine innings and four earned runs is a 4.00 and is not a quality start, while six innings and three earned runs is a 4.50 and is. The table above works six lines of it. The usual reply — that most quality starts are much better than the minimum — is probably right, and this page quotes no number for it, because the source that works the criticism does not give one and the alternative would be inventing a figure. What SABR does give is a usage fact: quality starts fell to “an all-time low of 41 percent” of starts in 2018.
The threshold is six COMPLETE innings, and baseball writes a part-finished inning as a figure that looks like a decimal and is not one: a line reading 5.2 is five innings and two outs, which is 5 + 2/3 innings. This page therefore takes the complete innings and the outs as two fields, with the outs field capped at 2 because a third out finishes the inning and the figure rolls over. The reason for separating them here is NOT a rate — nothing on this card is divided by innings. It is that five innings and two outs fails the definition even with a shutout line, and a calculator that read 5.2 as a decimal would wrongly call it a quality start. The rate arithmetic that notation breaks is worked at eight workloads on the earned run average calculator, which probes the error from 0.13% to 233% and prints the spread, and the same trap in cricket’s notation is on the bowling economy, average and strike rate calculator.
This figure contains a judgement, not just a count. Rule 9.12 of the Official Baseball Rules leaves the error to the official scorer, and Rule 9.16 then has that same scorer reconstruct the inning as though the defence had played without errors or passed balls to decide which runs were earned. Two scorers can watch the same inning and file different numbers, and nothing in the arithmetic can recover the difference. On a rate that judgement moves the answer by a hundredth or two. Here it flips a verdict: a single run reclassified from earned to unearned turns a four-earned-run outing into a quality start, and turns the pitcher’s line in a season total from one column to another. A statistic built on a threshold is more sensitive to a scorer’s decision than the rate it replaces, not less — which is a point neither MLB’s glossary nor SABR makes and which follows directly from the shape of the definition. The fielding side of the same decision is on the fielding percentage and range factor calculator.
One more limit, and it is the brief this site writes to. The six innings are two thirds of a nine-inning game, and nine innings is Major League Baseball’s regulation length rather than baseball’s. US high school games are seven innings under NFHS Rule 4-2-1, and Major League Baseball itself played seven-inning doubleheaders in 2020 and 2021. A six-inning start is six sevenths of one of those games, and no seven-inning version of the quality-start definition was found in anything read for this page — so this page does not invent one and does not apply the nine-inning threshold to a seven-inning game. Which lengths belong to which competition, with the dates they changed, is on the game length and extra innings interpreter. The other credited verdict about a single relief appearance, which IS in the rulebook, is the save rule interpreter, and the count-based limits on how long a young pitcher may be left in are on the pitch count and rest interpreter.
Frequently asked questions
What counts as a quality start?
At least six complete innings with three or fewer earned runs, in MLB’s glossary’s words “at least six innings and allows three earned runs or fewer”. It is a yes or a no about one start, it says nothing about how far past either threshold the outing went, and it appears in no rulebook — John Lowe of the Philadelphia Inquirer coined it in 1985.
Why do people say a quality start is a 4.50 ERA?
Because the minimum qualifying outing is exactly that. Three earned runs over six innings is three times nine divided by six, which is 4.50. SABR prints the objection as “Three runs in six innings? That’s a 4.50 ERA! In what world is that a measure of quality?” That is the floor of the definition rather than the average quality start, and no source read for this page quantifies how much better the average one is.
Is 5.2 innings a quality start?
No, whatever the runs. A line reading 5.2 is five innings and two outs — five and two thirds — and the definition asks for six complete innings. So a scoreless five and two thirds is not a quality start while six innings and three earned runs is, which is the clearest case of the threshold ranking two starts the wrong way round.
Is the quality start an official statistic?
Major League Baseball publishes it in its statistics glossary, and the Official Baseball Rules do not define it. Rule 9.21 is the list of percentages the rulebook defines and the quality start is not among them. The win and the loss, by contrast, are rulebook decisions, which is part of why the quality start was invented — to argue that a won-lost record describes a pitcher badly.
What are a tough loss and a cheap win?
A tough loss is a quality start the pitcher lost; a cheap win is a victory in a start that was not a quality start. MLB’s glossary credits John Lowe with both terms alongside the quality start itself. This page names them from the decision field, treating a tough loss as a quality start with at most one earned run.
Does a quality start mean the same thing in a seven-inning game?
Not obviously, and this page does not pretend otherwise. Six innings is two thirds of a nine-inning game and six sevenths of a seven-inning one, and no seven-inning version of the definition appears in anything read here. US high school games are seven innings under NFHS Rule 4-2-1 and MLB played seven-inning doubleheaders in 2020 and 2021.
Related calculators
References
- Major League Baseball. Glossary: Quality Start (QS) — “A starting pitcher records a quality start when he pitches at least six innings and allows three earned runs or fewer”, and “The quality start statistic helps to quantify which pitchers did a ‘quality’ job in those two departments.” It credits John Lowe of the Philadelphia Inquirer with coining the term in 1985 and with the companion labels “tough losses” and “cheap wins”. It cites no rule number and states no criticism of the statistic at all. mlb.com (read 15 Oct 2026).
- Mains A. “The state of the quality start.” SABR, sabr.org — gives the definition as a “quality start—defined as a start lasting six or more innings with three or fewer earned runs allowed”, credits it to Philadelphia Inquirer writer John Lowe in December 1985, and prints the standing objection in its own words: “Three runs in six innings? That’s a 4.50 ERA! In what world is that a measure of quality?” It reports quality starts falling to “an all-time low of 41 percent” of starts in 2018. It gives no figure for the average earned run average actually recorded in quality starts, so none is quoted here (read 15 Oct 2026).
- Official Baseball Rules, Rule 9.16, Earned Runs and Runs Allowed — “An earned run is a run for which a pitcher is held accountable”, charged only where it did not score through errors or passed balls; the official scorer reconstructs the inning as though the defence had played without them, a pitcher’s own error counts like any other, and the pitcher gets the benefit of the doubt. baseballrulesacademy.com (read 12 Oct 2026).
- Official Baseball Rules, Rule 9.21, Determining Percentage Records — (a) winning percentage; (b) batting average, hits ÷ times at bat; (c) slugging percentage, total bases on safe hits ÷ at-bats; (d) fielding average, putouts plus assists ÷ total chances (putouts, assists, errors); (e) earned-run average, earned runs × 9 ÷ innings pitched, with a Comment working 3 earned runs in 9 1/3 innings as 2.89; (f) on-base percentage, hits plus walks plus hit-by-pitches ÷ at-bats plus walks plus hit-by-pitches plus sacrifice flies. Read on baseballrulesacademy.com, 12 Oct 2026: the official 2024 Edition PDF was fetched whole and its extracted text of 109,942 characters stops inside Rule 5.09, while its own contents page lists Rule 9.21 on page 141. Every formula taken from it is corroborated against MLB’s glossary.
- Major League Baseball. Glossary: Earned Run Average (ERA) — ERA “represents the number of earned runs a pitcher allows per nine innings”, “with earned runs being any runs that scored without the aid of an error or a passed ball”, and “The formula for finding ERA is: 9 x earned runs / innings pitched.” It does not explain the 9. mlb.com (read 12 Oct 2026).
- Major League Baseball. Glossary: Innings Pitched (IP) — “Because there are three outs in an inning, each out recorded represents one-third of an inning pitched.” The entry does NOT state the “.1 and .2” scorebook notation, so this page demonstrates the notation from published lines instead. mlb.com (read 12 Oct 2026).
- National Federation of State High School Associations. NFHS Baseball Rules, Rule 4-2-1 — “A regulation interscholastic game consists of seven innings (turns at bat)”. Read on baseballrulesacademy.com, 12 Oct 2026; that reproduction carries no edition year, so the seven innings are cited as the NFHS’s standing rule rather than dated to a season.