Austin Riley started off his rookie season by blasting everything he got his bat on into the bleachers. Through his first six weeks in the bigs, Riley sported a .280/.333/.596 triple slash with an obscene 14 HR in 177 PA. What was equally absurd were 32.2 K% and 20.2 SwStr% rates, but when you’re posting .300+ ISOs those contact issues can be hidden.
The next three months were, unfortunately, a nightmare. The power disappeared, the strikeout and whiff rates somehow increased, and when it was all said and done Riley had slashed .150/.202/.293 over his final 123 PA. The convenient narrative was that Riley’s complete inability to hit sliders was exposed, and he could never adjust. While the slugger’s much maligned struggles with the slider were accurate, a more disturbing issue contributed as much, if not more, to his post-June swoon: a complete erosion of productive contact on four seam fastballs.
My friend Ivan the Great wrote an excellent piece about it at Talking Chop, and here’s a table that illustrates how much he was mashing four seamers through his first 40 games, and how much he struggled with them for the remainder of his rookie season.
To try and understand this rapid erosion of contact quality, I took a look at Austin Riley’s swing mechanics. A long hand load has been a feature of his swing throughout his development, but teams appeared to have successfully exploited it midway through his rookie campaign.
Watch him swing through the game-ending 96 mph fastball thrown by Ian Kennedy above, and you can see how long it took for him to clear his front shoulder with this swing. The ball gets about halfway to the plate before Riley plants his front foot and starts to drive through the zone.
Pro scouting reports got in, and if I had to presuppose their contents, the bulk of it focused on how his hand load and spin recognition created a big vulnerability to major league caliber heat if he wasn’t sitting on it.
In the Fangraphs’ rolling average chart below, note the increase of four-seam usage and decline of slider usage in the time leading up to and during his steep decline in offensive production. A constant throughout Riley’s rookie season were whiffs, but any additional pause seriously diminished his ability to make hard contact on those fastballs. Once that pause was exploited, overall production plummeted.
It’s always very important to do research and try to find if a player is working on anything in the off-season. As luck would have it, Riley was recently interviewed by AJC writer Zach Koons, and discussed changes he was making to his swing. Notably, he mentioned working on incorporating more even weight distribution in his lower half to help him drive balls he was late to, and keeping his front elbow from dropping to clear it quicker.
After learning about specifics, it seems like the Braves are focused more on small tweaks than wholesale changes — tweaks that will hopefully improve opposite field contact quality and contact rate altogether. David O’Brien of The Athletic recently tweeted out a video of Riley’s BP at the Braves’ North Port Spring Training Complex, and you can see marked improvement in the areas that he worked on with minor league hitting coordinator Mike Brumley this winter.
A true test of these changes will be rapidly approaching--live at bats in spring training competition--and the 2020 regular season will serve as a final exam. Let’s see if Austin Riley is an ace student.