In the seventh inning of the Cubs’ August 23rd game home against Baltimore, very potent infield prospect Javier Baez hit the seventh home run of his career in just his 82nd plate appearance. This impressive and immediate exhibition of power wasn’t particularly surprising. Both Baez’s minor-league numbers and the scouting reports suggested that, upon his promotion to the majors, that the 21-year-old Puerto Rico native would likely homer and strike out at rates considerably higher than league average.

Since that August 23rd plate appearance, Baez has continued to strike out at a nearly identical pace (41.5% before, 42.4% after). Instead of homering once every 12 plate appearances, however, what he’s done is homer zero times in 66 plate appearances — a rate which the reader will immediately recognize both as (a) worse and also (b) less good.

For a hitter well into his career, this probably wouldn’t merit much attention. Fly balls don’t become home runs at a regular rate, so, even for those players for whom power is an above-average skill, there will be extended periods of homerless-ness. For a player such as Baez, however — that is, one who features a singular offensive skill set and to whom the league is just becoming accustomed — there’s probably something to be learned even from these small samples.

Indeed, opposing pitchers appear to have changed their approach to Baez considerably. Regard the following table, where Before denotes the time period up to and including Baez’s seventh home run and After denotes the time period after it:

Included here are both the rate of four-seam fastballs seen by Baez and also his overall ground-ball rate during the relevant range of time. The league-average figures are 34.8% and 44.9%, respectively, for those metrics — which is to say, through his initial set of productive plate appearances, Baez actually saw slightly more four-seam fastballs than a typical major leaguer and also hit many fewer ground balls. Since then, however, Baez has seen a shockingly low number of four-seam fastballs and has had difficulty converting the pitches he has seen into fly balls and line drives — necessary conditions, those sorts of batted balls, to producing home runs.

How few four-seamers has Baez seen? Consider this one fact: the lowest rate among qualified batters is Pedro Alvarez’s figure of 27.1%. And consider this other one, too: over the last two weeks, only one out of 171 qualified batters (Jose Abreu) has faced fewer four-seam fastballs than Javier Baez. And this third fact, in conclusion: over the same two weeks in question, Baez has recorded the second-highest ground-ball rate among the aforementioned 171 qualified batters.

Ultimately, it’s incumbent upon Baez — for his main asset (i.e. power) to manifest itself — it’s incumbent upon him to hit the ball skyward. If he’s able to begin doing that again is what we’re about to find out.