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Fantasy Baseball: When Is It Time To Drop A Pitcher?

A hurler that is good and young is a valuable fantasy commodity, especially in dynasty leagues. However, they are more volatile than hitters, in many senses: their careers and primes are usually shorter because of the stress that is constantly put on their arms. Injuries, ineffectiveness, and wear and tear may appear. We recently analyzed what to do with hitters, but when is the right time to drop a pitcher from your fantasy squad?

Whether it is your early-round selection, a late pick or a waiver wire addition, it is not uncommon that a pitcher tests our patience. Knowing when to cut the cord can save you from holding on to a declining asset.

As usual, savvy fantasy owners often look under the hood to see if a pitcher is worth keeping or if it is time to say goodbye. And, as usual, the sample size of a specific stat will tell us a lot.

The Role of Sample Size in Knowing When to Drop a Pitcher

The number of batters faced, balls in play, at-bats or fly balls we use to evaluate a player’s performance is our sample size. That’s the data we fantasy players work with, and as it happens in other experiments in life, the more we have, the better.

In small sample sizes, we could see “fluky” results that aren’t credible or may be considered as such but more data is needed to validate a specific conclusion. After all, we want to minimize or eliminate those random factors. Lots of pitchers are capable of having a fantastic three-start stint, but if we have a larger sample size, we can know more about possible future performance. The stabilization point, which is the moment when we can consider that luck and random factors aren’t affecting the outcome of plays or events, varies from stat to stat.

It’s easy to translate this to the fantasy world. If a pitcher has three consecutive 10+ strikeout games, we need to start paying attention. On the other hand, if our mid-round selection gives up at least five earned runs in a five-start span, we may be about to drop a pitcher we will later regret.

Don’t panic! Look at these stabilization points that our friends at Fangraphs have established:

“Stabilization” Points for Pitchers:

Strikeout rate – 70 BF

Walk rate – 170 BF

HBP rate – 640 BF

Single rate – 670 BF

XBH rate – 1450 BF

HR rate – 1320 BF

AVG – 630 BF

OBP – 540 BF

SLG – 550 AB

ISO – 630 AB

GB rate – 70 BIP

FB rate – 70 BIP

LD rate – 650 BIP

HR per FB – 400 FB

BABIP – 2000 BIP

How do we use this information? Well, the first thing that jumps out to the eye is that the strikeout rate is the stat that stabilizes the fastest among all the useful ones. Personally, I like strikeout rate, walk rate, GB rate, FB rate, and BABIP.

Think about 2019 Matt Boyd, for example. He started off the season with a 10-K performance against the Toronto Blue Jays and a 13-K gem versus the New York Yankees. He faced 48 batters in those two games.

After his next start, a 6-K performance against the Cleveland Indians, he had reached 72 batters faced. From that point on, we can feel more confident about his ability to strike people out, and we can make roster decisions accordingly. His ERA may not be good and he sure didn’t win much in Detroit, but he sure can fan hitters, as evidenced by his 11.56 K/9 full-season rate.

BABIP, on the other hand, takes a very long time to stabilize. Maybe you shouldn’t wait for it to make a judgment on the success or sustainability of a pitcher. Not everybody can wait for 2000 balls in play. If you are tempted to drop a pitcher, there are more things you should look for other than BABIP.

Other Factors to Consider Before Deciding to Drop a Pitcher

Consider these factors, too, before you make the decision to drop a pitcher from your squad:

The Pitcher’s Age

Usually, we can know after a couple of starts if a team has brought up a prospect too soon. These very young pitchers can be safely dropped in shallow redraft leagues within a few weeks of play, especially if they don’t come with “top pitching prospect” pedigree.

I would recommend trying to exercise some patience if you took the pitcher in question early or even if he was a mid-round selection. Don’t forget to take the stabilization points into account, and if they are favorable, try to give the player a couple of months before releasing him.


There are pitchers that struggle more than others in lower temperatures, usually closer to the start of the season. It depends on the location and the hurler, of course.

As this article shows, “a cold, dry day has weather that would reduce the pitch movement just a bit, and then also makes the grip on the ball tougher to get right.”

However, as the piece also outlines, the hitter may also feel the effects of the low temperatures. It’s just a factor to help in your analysis.

What’s Under the Hood?

If you are about to drop a pitcher that is underperforming his ADP or killing your ratios, go to his Statcast profile. He may be getting extremely unlucky. How can we know this for sure? Well, we can’t. but we can have a very good idea by looking at his average exit velocity, hard-hit rate, and other stats.

If a pitcher has allowed 15 earned runs in his last 22 innings, we may be about to reach a point of no return. However, if his average exit velocity is 86 mph, and his hard-hit rate is 33 percent, then he can easily receive some positive regression in the short-term.

Also, look at the HR/FB. If a hurler has an absurdly high figure, like 40 percent over a three-start stint that included two starts at Coors Field and one in Yankee Stadium, that is bound to come down to earth. Don’t panic and hit the “drop” button before considering these things.

The expected weighted on-base average (xwOBA) is one of my favorite resources. It removes defense and ballpark from the equation, focusing on exit velocity and launch angle while also adding walks and strikeouts. The xwOBA helps us decrease the luck factor that may be included in the outcome of a play. Be on the lookout for possible xwOBA-wOBA disparities before considering the exact moment when to drop a pitcher.

If a hurler has a .290 wOBA but a .335 xwOBA, he is getting very lucky. If he shows a .347 wOBA, but his xWOBA is at .305, better days are probably ahead.

Pay attention, dynasty leaguers! For reference, Mitch Keller had the largest positive wOBA-xwOBA differential of all pitchers, with .078. His wOBA was .392, but his xwOBA checked in at .314. He was extremely unlucky, and while that itself doesn’t explain his 2019 struggles, it helps.

Closeness to Prime

Generally, I don’t like to drop a pitcher that has been successful recently and is at or near his prime.

For example, fantasy owners that cut the cord with Yu Darvish after his horrid first half (5.01 ERA) missed his fantastic second-half run (2.76 ERA.) The same could be said about Jack Flaherty.

The former is closer to the end of his prime, at 33, and the latter is just entering his, at 24. But both have been very successful recently, and if you cut them early… well, shame on you.

League Format

We know you are tired of seeing “2.1 IP, 5 ER” lines from your starting pitcher. However, before kicking him to the curb, take a look at your league settings. League size matters. The difference between dynasty, keeper, and redraft matters, too. It’s not the same to drop Domingo German in an 8-team redraft than doing it in a 20-team keeper.

I hope you find all this information helpful when you think it’s time to drop a pitcher from your fantasy roster.

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