clock menu more-arrow no yes mobile

Filed under:

A complete beginner’s guide to baseball stats: Pitching statistics, and what they mean


Detroit Tigers v Milwaukee Brewers Photo by Stacy Revere/Getty Images

Pitching is a complicated process. Pitchers can use a combination of at least a half-dozen pitches, with different spin rates, into different locations in the strikezone, with a variety of outcomes. The result is a plethora of stats that can befuddle casual baseball fans. We will take a deep dive into the more advanced stats later in the week, but for now we want to make sure all the basics have been covered.

So, we’ll start with our good friend the box score, and then touch on a few other key pitching statistics, to make sure you have a good groundwork in place before we get too deep into the rest of it.

Once again we’ll be using the example of the July 10, 2018 game against the Tampa Bay Rays.

Courtesy of ESPN

Pitching Basics

Innings pitched (IP)

The number here represents how many innings a pitcher went into a game. For Matthew Boyd, above, he pitched a full six innings. You may sometimes see the innings pitch listed as 6.1 or 6.2. These decimal points tell us how many outs into an inning the pitcher went. If a pitcher has a 6.1 under their innings pitched, it means they pitched six complete innings and got one batter out in the seventh before being pulled for another pitcher. You will only see a .1 or .2, because a third out would finish the inning.

Hits (H), Runs (R), and Earned Runs (ER)

Hits, here, are the same as they are for a batter. Any time a batter reaches at least first base, excluding errors and fielder’s choice. We discussed this in more detail in our batting 101 primer.

Runs, again, are the same as for a batter, and indicate any time the batter reaches home plate and scores a run.

Earned runs (ER) is a stat exclusive to pitchers, and indicates that the run scored was a direct result of batter’s efforts. Almost all runs are earned runs, with the exclusion of runs scored as a result of a defensive error or passed ball. These are considered unearned runs, because they were not scored as a result of the batter’s efforts. Both types of runs are counted for pitchers, but only earned runs are factored into a pitcher’s earned run average (ERA). For example, in 2018 Matthew Boyd has 87 runs on his record, but only 83 earned runs.

Base on balls (BB), strikes (K), and home runs (HR)

These are all pretty self-explanatory stats. Walks, or base on balls (BB) indicates how many batters were walked by the pitcher. This total will included intentional walks (IBB). Strikes indicate the number of batters that a pitcher struck out in the game. Home runs are the number of home runs given up by the pitcher.

Pitch count (PC) and Strikes (ST)

This number is exclusive to box scores, but still offers some vital insight onto how well an individual game went for a pitcher. Pitch count is how many total pitches were thrown by a pitcher, while strikes counts how many of each of those pitches were called a strike by the home plate umpire.

Wins (W) and losses (L)

We can see above that Matthew Boyd is considered the losing pitcher for this game. The L, and 4-8 behind his name indicate that he took the loss, and that his season record is four wins and eight losses.

A win or loss is calculated based on which pitcher was on the mound for the team when their team took the lead. Or, conversely, which pitcher was on the mound who gave up the lead in the game. Let’s look at the Rays side of the box score for a better explanation.

Courtesy of ESPN

Ryne Stanek started the game, and did not give up any runs, but he is not the winning pitcher for the game. Jose Alvarado gets that nod because he was pitching during the third inning of the game, during which the Rays scored all five of their runs for the game. Therefore Alvarado was the pitcher on the mound when the Rays took the lead in the game.

The “S” in brackets behind Sergio Romo’s name represents a save. A save is collected when the pitcher to end the game limits a potential tying game, or opposition win. Not every game ends in a save situation. The above example saw the Tigers score two runs in the top of the ninth inning, before Adam Kolarek was pulled for Sergio Romo. Romo entered the game with a three run lead, putting the game in a save situation. Three is the maximum number of runs of a lead to count as a save situation. Likewise, it would be considered a save if Romo came on with the bases loaded and the typing run on deck or at the plate.

This would be a good place to mention holds. A hold is collected when a middle reliever enters the game with his team in the lead, and does not give up a tying or advancing run before handing the ball off to another pitcher. Basically, if a middle reliever keeps his team in the lead, he collects a hold. Holds are rarely tracked in player statistics, but are often mentioned in a box score, sometimes with the abbreviation HLD.

Both saves and wins are rather contentious statistics, as wins do not really fairly represent a pitcher’s quality. Just look at 2018 NL Cy Young winner, who started in 32 games, but won only 10 of them. This was certainly not the fault of his incredible pitching, and yet wins remain a metric by which many Cy Young voters measure the quality of a season.

Pitching Averages

Earned run average (ERA)

Earned run average is one of those stats where the lower it is, the better the pitcher. A pitcher’s ERA is calculated by the number of earned runs they’ve allowed (ER), divided by the number of innings pitched (IP) multiplied by 9 (the traditional inning length of a game).

As mentioned above, unearned runs are not factored into this number, giving it a more realistic feel for a pitcher’s success. ERA is probably one of the most commonly used pitcher stats, but it is no longer considered to be the most accurate representation of a pitcher’s actual quality. There are two examples below of other common pitching metrics which some believe offer a more fair assessment of pitcher quality.

Field Independent Pitching (FIP)

Field independent pitching attempts to remove defensive fielding factors from a pitcher’s performance, in order to better represent a pitcher’s true value when taken independently of the team’s defense.

FIP looks at factors controlled by the pitcher: strikes, walks, hit by pitches, and home runs. What’s nice about FIP is that it’s represented in a number that looks almost identical it ERA, but is a truer representation of a pitcher’s performance. If we can understand that Blaine Hardy’s 3.56 ERA is good, we can look at his 3.97 FIP and see that it is still a decent number, but not as good as his ERA, indicating he was helped somewhat by the Tigers defense. Michael Fulmer, on the other hand, had a 4.69 ERA and a 4.52 FIP, which tells us his true results as a pitcher are somewhat better than his ERA would indicate.

The formula for calculating FIP gives me high school calculus flashbacks.

Courtesy of FanGraphs

FIP is not a perfect measurement of pitcher quality, but it is a more accurate depiction of a pitcher’s individual skill than ERA is.

Adjusted ERA (ERA+)

Like OPS+, Adjusted ERA attempts to factor a pitcher’s home ballpark into the equation (which can be beneficial to pitchers who work in a hitter-friendly park, and negatively impact pitchers in a pitcher-friendly park). Also like OPS+ the league average is set at 100, and whatever amount over that number a pitcher collects is their percentage improvement over the league average. Jacob deGrom, for example, had only 10 wins, but an ERA+ of 216, meaning he was 116% better than league average.

ERA+ is calculated by factoring in a player’s ERA, divided by league ERA, and then accounting for park factors. The formula looks like this:

Courtesy of Wikipedia

Walks plus hits per inning pitched (WHIP)

You have to love a stat where the name really tells you exactly what to expect. Walks plus hits per inning pitched is precisely that, a calculate of the number of baserunners allowed by a pitcher per inning of work. The lower a WHIP, the fewer baserunners allowed by a pitcher.

WHIP is calculated by adding hits and walks and dividing it by innings pitched. A WHIP under 1.000 is considered exceptional for a season. deGrom had a 0.912 WHIP in 2018. Justin Verlander had a 0.902 (the lowest WHIP in his entire career).

WHIP isn’t a great all-encompassing pitcher stat, but it is often included in a pitcher’s overall season stats because it’s a very quick way to see how successful a pitcher is against batters. WHIP is basically the opposite of OBP, in that the lower a pitcher’s WHIP, the fewer batters are reaching base against him.

Was that too much math? For me, too, honestly.

If this has you excited to learn more about pitching stats, we will be doing an advanced pitching breakdown later in the week.