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How to Evaluate Late-Season Streaks or Slumps (Fantasy Baseball)

by Josh Shepardson | @BChad50 | Featured Writer
Jun 27, 2019

Underlying stats suggest Arenado should see regression in the second half

As is always the case, gamers should consider context and sample size when evaluating any player’s stats. However, late-season numbers tend to receive extra attention. From a logical standpoint, it makes sense. Recency bias plays a hand in the decision making of fantasy baseball gamers all the time. Having said that, the end of a season creates a unique dynamic since it leads directly into the offseason. Players won’t have an opportunity to cool off or turnaround slumps before gamers and fantasy baseball pundits alike begin building player rankings lists for the following season. Gamers will be left to stew on the most recent work of players, and they’ll have months to do so. It’s important to understand how late-season happenings shape narratives, and it’s paramount gamers sift through the noise to make more informed decisions. Avoiding lazy analysis can result in scooping up bargains and avoiding overvalued players.

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Frequently young players who finish a season with a flurry will be the subject of breakout pieces and generate the most buzz in fantasy baseball circles. Conversely, young players or older veterans near the end of their careers who slump at the end of the season will find themselves tumbling in the rankings and the subjects of cautionary articles. The narrative surrounding the young players will be that the league has adjusted or figured them out, and the speculation with older players is that they have little to nothing left in the tank and are on the verge of a cliff season. These narratives often result in helium carrying young players coming off of a big finish up draft boards while the struggling youngsters and veterans topple down boards. Sometimes the player movement for those respective categories of players is warranted, but it’s a mistake for gamers to blindly follow those narratives without digging deeper into the numbers.

One piece of context that gamers will have to consider for players finishing the year on a high note — at least for one more season — is the quality of competition faced. For the 2019 season, MLB teams will still have 40-man active rosters from September 1 through the end of the regular season. Starting in 2020, teams will have a 26-man active roster (teams currently have 25-man active rosters) starting Opening Day and running through August 31 before giving way to 28-man active rosters from September 1 through the end of the regular season. You can read about that rule change (and others) in this piece from Baseball AmericaFor at least one more year, it’s possible pitchers cruising to the finish line face an unusually high number of bad lineups featuring guys who aren’t big-league ready but are getting a taste of a big-league cup of joe as a result of 40-man active roster usage. The most egregiously terrible lineups that fall under this category are the “hangover lineups” teams trot out the day after clinching a division or Wild Card berth. It’s also possible for hot-finishing hitters to spend the end of a year feasting on below-average starting pitchers. For instance, rebuilding teams could take the opportunity to evaluate young starters who might not yet be ready, and teams that have clinched a playoff berth could opt to rest their top starting pitchers in advance of the playoffs by using bottom-of-the-roster starters to soak up innings.

Level of competition is just one variable to consider for a player’s end-of-season numbers. Another consideration is the health of players. The MLB season is a grind, and players often play at less than 100%. Teams and players sometimes disclose injuries that players played through after the season. Can that injury be traced back specifically to a hit-by-pitch, for instance? If it can and a slump immediately followed that incident, a slump could be fully or partially explained by the player playing banged up. Sometimes it’s difficult or impossible to locate a specific incident leading to injury, but a player finishing the year on a down note with a later disclosed injury makes for a potential buy-low if he falls in the rankings.

In addition to considering context, gamers should do a deep dive into the underlying numbers of a late-season slump or heater. If a pitcher dominates the opposition at the end of a season and they enjoy an increase in velocity during that stretch and/or they add a pitch to their repertoire or drastically change their mix of pitch usage, I’m more inclined to buy into their success being sustainable than a pitcher making little to no tangible changes while posting better numbers. Conversely, if a pitcher’s velocity takes a nosedive and they get knocked around at the end of the season, they carry a red flag into the following season, and reports on their velocity in the spring should be monitored closely. For hitters, plate discipline numbers and batted ball type (specifically groundballs and flyballs since line drives are volatile and take a long time to normalize) are the information I put the most weight in. For example, it’s easier to believe in a hitter’s homer binge to wrap up a season being a harbinger of more homers the following season if they hit more balls in the air as opposed to simply benefiting from a HR/FB% surge. The running joke of not dropping your first-round pick in the first month of the season for a free-agent who’s off to a hot start is an idea that can be applied to handling late-season statistics. Don’t be fooled by recency bias without evaluating context and digging deeper.

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Josh Shepardson is a featured writer at FantasyPros. For more from Josh, check out his archive and follow him @BChad50.

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