One of the key conversations going on this spring has been what numbers can drafters trust from the curtailed 2020 season? What slumps are more than a bad few weeks? Which breakouts are real progression and not just a hot streak? We won’t know the answers until the games play out. The Fly Index metric that Brian Creagh and I have explored in past seasons may help us make better guesses at the reliable power from 2020.

To recap Fly Index for those unfamiliar, it is the distance of the 85% batted ball event for a hitter. Brian found that there’s a correlation to home runs and that fly ball distance point. It makes sense. If a hitter is hitting fly balls often and far, they’re more likely to have increased home runs. You can have a look for yourself on Brian’s Tableau page but I wanted to point out some hitters I’d trust, doubt, and look to for a rebound.


  • Fernando Tatis Jr. - I’m sure I don’t have to sell you on one of the most electric hitters in the game. It’s nice to see that his Fly Index increased with the HR% remaining consistent. He’ll grow into that power nicely.

  • Mike Yastrzemski - In his two seasons, Yaz has posted a home run rate of 7.8% and 7.3%, with a Fly Index of 374 and 366. That consistency is wonderful to see. His home park obviously hurts, but they closed the archway’s last year and could again in 2021. That makes it less of a power death sentence.

  • Eugenio Suárez - All Suarez does is mash fly balls in a small ballpark. He always seems on pace for 40 HRs. A Fly Index consistently north of 350 supports trust in that.


  • Rowdy Tellez - Tellez is a prime small sample candidate. He cut his K% practically in half and upped his average fifty points. His HR% was a three year high and with a weak Fly Index of 338. It's a huge concern beyond that.

  • Manny Machado - Here’s another 2020 jump I have doubts on. Machado’s Fly Index fell to 331 while his HR% jumped from a previously steady rate. His launch angle did increase along with the homer jump so there’s a chance the skills change holds.

  • Kyle Lewis - We don’t have prior years to contrast Lewis’s breakout with but a 335 Fly Index is cause for concern. We’ll get to see how much the second half collapse factored into that in his first full season.


  • J.D. Martinez - JDM is one of the easiest buy low opportunities we’ll ever see. Most of his peripherals stayed strong but the HR% was cut in half from 8.1% to 3.9%. That includes a solid Fly Index of 366 in 2020. Some strange (bad) luck happened here.

  • Jorge Soler - During his 48 homer 2019, Soler posted a big 377 Fly Index. His home run pace dropped in 2020 but he still had a healthy Fly Index of 373. I wouldn’t bet on him approaching 50 again, but there’s plenty of room for value at his cost.

  • Justin Turner - Turner’s year to year numbers are a bit more erratic, most likely due to a myriad of health issues. That will always be the drawback with rostering him. His Fly Index stayed steady from 356 in 2019 to 353 in 2020, however. A dip in HR% from 7% to 3.1% could be flukey.

Those are just a few names that stood out to us. The chart below can be broken into quadrants. Top right is hitters that performed well and had a good Fly Index. Top left is a strong Fly Index but weaker HR%, meaning some degree of bad luck. Below and right of the line are home run rates that could be hard to maintain.