Baseball 101: Beginner pitching statistics

This time we’ll look at the pitching side of things.

Welcome back to our ongoing series about introducing the basics of statistics and baseball in general to new fans (or old fans looking to brush up on their knowledge). Today we’re continuing with the most basic statistical information, but this time looking at pitchers. We previously did this for batters, and you can find that information here.

I mention the batting article because in that we discussed the basics of strikes, balls, walks, and runs, which may be valuable information to read through going into this piece, since I won’t be re-explaining those particular facets.

After this entry we’ll start to get into some more advanced stats, so get ready, get excited, and let’s keep learning together.

First, let’s talk a little about pitchers. In our “player positions” breakdown piece, I mentioned that there were typically two types of pitchers: starting pitchers and relief pitchers. Your starting pitchers are expected to go as many innings as possible (though fatigue or injury may cause them to exit the game earlier than hoped for). Once a starting pitcher is out of the game, the manager will turn to the “bullpen” which is the name for the warm-up area where relief pitchers prepare to enter the game.

Relief pitchers can be “long relief” guys, who are capable of stepping in to cover multiple innings, similar to a starter. There are also “short relief” pitchers who are more specialized and may only come on to face the minimum number of batters (3) or to perform in a specific inning. The best-known kind of short relief pitcher is a “closer.” A closer will be used in the ninth inning of a high-leverage game, usually when the score is either very close, or that team holds a narrow lead. The job of the closer is to be able to keep the opposing team from scoring any runs in a particularly high-stress scenario.

Another key difference between starting pitchers and relief pitchers is the number of pitch types they throw. We’ll get into pitch types in a later entry, but in most situations, a starting pitcher will throw a mix of four or five pitches confidently. It’s this flexible repertoire of pitches that allows starters to go so long into games, because the batters are less likely to know what’s coming two or three times through the batting order. There is one exception to this, and that’s with knuckleball pitchers. They can be starters while throwing only one pitch, because knuckleballs are notoriously difficult to track and difficult to hit. However strictly knuckleball pitchers are exceedingly rare.

Relief pitchers, unlike starters, will usually have a good command on one or two pitches that they lean most heavily on, and that’s why it’s best to use them over shorter stretches, as the batters will likely know what’s coming if they get through the order a second time.

Now that we’ve established a basic understanding of pitcher types, let’s look at some of the stats you might see used to describe their performance.

Innings Pitched (IP)

When we discussed batters, we looked at plate appearances and at-bats. Innings pitched looks at pitcher performance over the entirety of an inning, rather than by the number of batters faced. The number here represents how many innings a pitcher went into a game. This number can be confusing for new fans because of the decimals. Logic would suggest that a decimal should be one of ten, but in baseball it’s actually one of three, and each one of those three represents a batter. If you’re confused, don’t worry.

These decimal points tell us how many outs into an inning the pitcher went. Since there are a maximum of three outs per inning, the decimal can only be .1 or .2. It might be easier to think of them as ¹⁄₃ because that’s how we would say it out loud. If a pitcher has a 6.1 under their innings pitched, it means they pitched six complete innings in a game and got one batter out in the seventh before being pulled for another pitcher. We would say they went “six and ¹⁄₃ innings.” You will only see a .1 or .2, because a third out would finish the inning, giving us a complete number.

Earned runs (ER)

We won’t discuss hits and walks, because we explained those with batting stas, and they are the same here. Earned runs is a stat exclusive to pitchers, though, 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 2021 Ryan Yarbrough had 96 runs on record, but only 88 were earned runs, meaning the others were the result of defensive errors of some kind. The difference between earned and unearned runs is tracked because analysts want to fairly calculate pitcher performance, and it would be unfair to count runs against them that were not their “fault.”

We’ll get to ERA in a moment.

Pitch count (PC) and Strikes (ST)

This number is exclusive to box scores, but offers some insight into 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.

The idea of this is to let us see how frequently a pitcher was successfully hitting the strike zone with his pitches and getting the most desirable outcome: a strike. The higher the number of strikes-to-pitches, the better that pitcher’s performance likely was.

Wins (W) and losses (L)

In every game, there is a winning pitcher and a losing pitcher, just as there is a winning and losing team. However, the winning pitcher is not necessarily going to be the one who pitched the longest, or even the best.

A win or loss is calculated based on which pitcher was on the mound for the team when their team took the lead. Or, if we’re looking at the losing side, which pitcher was on the mound who gave up the lead in the game.

There are some other abbreviations you might see in a box score that are worth noting as well. An “S” in brackets behind a player’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. Three is the maximum number of runs of a lead to count as a save situation.

We can also mention holds, here, as they’re in the same family as saves. A hold is collected when a middle reliever (someone who isn’t the starter or the closer) 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 they can be mentioned in a box score, with the abbreviation HLD, which is why we’re mentioning them here.

Both saves and wins are rather contentious statistics, as wins do not really fairly represent a pitcher’s quality. You may often hear baseball fans saying “wins don’t count” and they’re not referring to won games, but rather the number of games “won” by certain pitchers.

Now that we have the basics under our belt, let’s look at three actual “stats.”

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 we mentioned above, unearned runs are not factored into this number, which allows it to most accurately reflect a pitcher’s success or failure. ERA is one of, if not 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. (I am personally a big fan of SIERA, but it’s an advanced stat that almost no one uses, so we’ll save that for another day).

Field Independent Pitching (FIP)

Field independent pitching is becoming a much more commonly used stat in terms of describing the actual quality of individual pitching performance. What makes it different from ERA is that it attempts to remove defensive fielding factors from a pitcher’s performance, in order to more accurately represent a pitcher’s true value when taken independently of the team’s defense.

Yeah, that was a mouthful, but basically: how good is a pitcher if we take out those amazing center field catches or that sensational shortstop who scoops up all those groundballs? Conversely, how good would a pitcher on a defensively poor team be if his outfielders could actually catch things over the fence?

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. For example we can look at a pitcher whose has a 3.14 ERA and think they are pretty good, but we can then look at his 3.87 FIP and see that while still solid, it’s not as good as his ERA, indicating he was helped somewhat by his team’s defense. On the other hand, a pitcher might have a 4.79 ERA and a 4.42 FIP, which tells us his true results as a pitcher are at least a little better than his ERA would suggest.

If you want to see how FIP is calculated, the FanGraphs stat library has a good breakdown.

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.

Walks plus hits per inning pitched (WHIP)

I’ll give it to WHIP, much like its batting cousin OPS, it really just tells you what it is right there in the name. Walks plus hits per inning pitched is just what it sounds like: a calculation of the number of baserunners allowed by a pitcher per inning of work. The lower the total WHIP, the fewer baserunners allowed.

WHIP is calculated by adding hits and walks and dividing them by innings pitched. Since this number looks a bit different from ERA and FIP, let’s define what a good seasonal WHIP looks like. A WHIP under 1.000 is considered exceptional. In 2021 Max Scherzer had a WHIP of 0.864 which was not only best in MLB, but best in Scherzer’s career to date. On the other hand, Dallas Keuchel had a 1.531 WHIP, which is... not great.

WHIP definitely isn’t a perfect 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.

With a combined understanding of ERA, FIP, and WHIP, you should now better be able to tell if a pitcher is doing well or poorly for the season.

And that, friends, is pitching basics. It’s okay to be a bit overwhelmed, that was a lot of information, but now you have a fundamental understanding of batting and pitching, which means you’re ready to start learning more advanced stats!

If you’d rather watch a video about the above information, here you go.