This week’s advanced stat is none other than my and Brian Creagh’s very own Fly Index. In case you missed my post earlier this spring detailing what Fly Index is I linked it. To summarize Fly Index, it is a player’s 85th percentile measure for batted-ball distance. Why the 85th percentile? We care about that tier of contact that isn't quite a home run. Sabermetrics OG Tom Tango came across our humble piece and aptly described it as barrels and near barrels. The 85th percentile seems to work really well because the top 5-to-7% are typically home runs. We want to account for that next tier of contact that isn't quite over the fence. The point of that being if a hitter is hitting balls with both frequency and distance, they are likely to produce power for fantasy.
Let’s take a look at the players hitting the ball in the air a long way. Below is the Fly Index leaderboard for players with at least twenty balls in play.
The truest sluggers to date have been Gary Sánchez , Dan Vogelbach, and Christian Yelich , unsurprisingly. A few names on this list with a low HR% and look like they could have an uptick: Hunter Dozier , Willians Astudillo, Paul DeJong , Franmil Reyes , Eddie Rosario , Nolan Arenado , and Yadier Molina . If Dozier can bump his launch angle up a hair we could have a breakout on our hands. Arenado will obviously be fine once he gets some more games played in the thin Colorado air. DeJong and Rosario are waking up at the plate as I write this. Franmil was fairly unlucky to start the year based on xwOBA and the results are starting to come. The two backstops are particularly intriguing in the wasteland that is fantasy catchers.
There are two sides to every coin. Who’s hot start should we be taking with a grain of salt? Here are the hitters that came out of the gate with a strong HR% over 9%.
The guys at the bottom are the ones to be concerned about. Asdrúbal Cabrera , Derek Dietrich , and Maikel Franco all have an accompanying exit velocity below 88, making them the primary offenders. Marcell Ozuna had a pretty cold start to the year so his numbers could stabilize. Joey Gallo ’s name is an interesting inclusion. My instinct tells me he’ll be ok. It’s a small sample after all.
As always, no single stat is king. Fly Index is a lens through which power can be evaluated. Some of these seemingly strong performers could flounder just as easily as the guys with questionable peripheral stats could normalize. We work with the information available and make the best fantasy decision we can. That Fly Index was more correlated to home runs from 2017 to 2018 than some go-to stats like barrel% makes a strong case for putting some stock in these players.
As always, a huge thank you to Brian Creagh for his work with the Statcast data and helping make Fly Index a reality.