Home Run to Flyball Rate (HR/FB) is one of the most straightforward statistics that we use for fantasy baseball since it's simply telling us what percentage of flyballs are hit for home runs. The metric is calculated by taking total home runs divided by total flyballs hit. The part that's not quite as straightforward is analyzing the metric once we have it calculated.
HR/FB rate can be influenced by a myriad of different things and thankfully the Statcast era is ripe with new tools that can be used to assess each player's underlying skillset to make determinations whether their counting stats are deserved or simply lucky. Traditionally, factors like weather, ballpark park factors, and batted ball location were perceived as key primary drivers in a player's ratio of home runs totals. Now, however, metrics like exit velocity, launch angle and batted ball distance quantify some of the qualities we used to only see with our eyes.
So why is analyzing HR/FB such a useful tool for fantasy baseball?
The simple answer is that it helps us test the performances of players to determine if home runs hit in a prior year were a reflection of a skill set that the player owns, or a reflection of good fortune based on one of the traditional factors I mentioned above.
In many people's eyes, the 2019 Major League Baseball season will go down in history as the year of the juiced ball. A quick search on the internet reveals endless theories why, but the sheer number of home runs hit in 2019 led to MLB officials hiring a team of forensic scientists to get to the bottom of the great ball debate. The official results of the MLB-commissioned study showed mixed results for the exact cause, but the forensic scientists did suggest the both lower seams on the baseball and a change in batter's launch angles are two of the most probable causes. While there's still no definitive answer, one thing we know for sure is that the ball is flying out of the park at historic rates.
The league-wide homerun-to-flyball rate (HR/FB) rate rose to 15.3% in 2020, up from 12.7% in 2019 and 1.7% higher than the next highest rate recorded in any other season.
As with the ball, there is already plenty of analysis around home runs and HR/FB floating around the internet, so I wanted to take it a step further and only look at the homerun data on hard hit flyballs with players that received enough at-bats in 2019 to stabilize their results. As a result below was my criteria for selecting my data:
-Only included players with 170 or more ABs (the point where HR% stabilizies)
-Only included flyballs (96% of all home runs hit in 2020 were flyballs)
-Only included BBE > 95 MPH (Statcast defines hard hit balls as hit with an EV > 95 MPH)
Once there, you'll also find that player's 90th percentile exit velocity on all flyballs, his 90th percentile home run distance, and his median launch angle. Using these metrics, we're able to paint a more complete picture of the skillset a player actually owns and therefore can better rationalize his overall HR/FB numbers. In general, players that have higher exit velocity and HR distance will be the same players that will be able to repeat power performances. Those that have lower exit velocities and lower home run distance are typically the players that are more reliant on weather (i.e wind/humidity) or park factors (i.e. short porches) to hit home runs. At that link, you'll also find a section where you can compare up to 10 players to compare these Statcast metrics against each other, which is a useful thing to do when you're in the draft room trying to decide between a few different choices.
Who are some names on the list that surprise you? What do their Statcast 90th percentile marks tell you about their performance?