Breaking down Yadier Molina's year-to-year performance against fastballs

It cannot be denied that St. Louis Cardinals catcher Yadier Molina has come a long way as a hitter in his major league career. What started as a Tony La Russa-driven narrative of Molina being an "all defense/leadership, very little offense" evolved into the indisputable fact that Molina was one of the league's top hitters at his position from 2011 through 2013. Yet, this has not been the case in the last two seasons (102 wRC+ in 2014, 80 in 2015), and this is likely due to a combination of advancing age (Molina is now 33 years old) and two significant thumb injuries.

In July 2014, Molina injured the thumb on his throwing hand while sliding into third base, causing him to miss nearly two months of game action. Molina was able to return from the injury, but his already decreasing power all but disappeared as he was able to swat only five extra base hits (all doubles) in 110 plate appearances to close out the regular season (.050 ISO). Thankfully, Molina had an entire offseason to rest and rebuild the strength around his right thumb.

By all reports, Molina arrived to spring training in good health, and no one talked about any lingering effects from 2014's thumb injury whatsoever. Rather, it seemed that most people were focused on his offseason weight loss. While Molina once again proved to be uncharacteristically durable for a catcher his age (he was on pace for a career-high for innings caught in a single season), his bat continued to lag behind from what we had grown used to in previous seasons. Molina did not hit his first home run of the season until June 15th against the Minnesota Twins—396 plate appearances (including postseason) after his last home run (a solo shot against the Los Angeles Dodgers on June 27th, 2014).

So, what is going on with Molina? The title should be suggestive of a possible answer, but before we get into results-based analysis, let's first discuss the process. The impact of Molina's thumb injuries cannot be understated. By now, we all know the stories of Mark DeRosa (2009 and beyond), Peter Bourjos (2014), and Jon Jay (2015). Each hitter, while with the Cardinals, struggled at the plate in the time after injuring their thumb and/or wrist. Admittedly, I am using thumb and wrist interchangeably here because they physiologically and anatomically intertwined.

Molina, while reportedly healthy for the first three-quarters of 2015, had a powerless bat. Sure, he maintained a respectable batting average, but this was largely achieved by slapping and spraying pitches to the opposite field. While I will not go as far as FiveThirtyEight in saying "Yadier Molina Forgot How to Hit a Fourseam Fastball," I must admit that we are witnessing a worrisome trend.

From 2011 through 2013 (which I will unofficially classify as Yadi's "prime hitting years"), Molina whiffed on 14.95% of swings against fourseam fastballs; since 2014, this whiff percentage has increased to 18.71%. It goes even deeper, too, as Molina's ground ball rate on fourseam fastballs put in play is up to 41.47% since 2014, a ~14% increase from 2011 through 2013, when it was 36.26%. Thus, not only is Molina swinging and missing more against pitches he used to mash (see the chart below), but when he does make contact, it often results in a grounder—the most difficult batted ball type to turn into an extra base hit.

And as you will see in the chart below, this is not something that just popped up in 2015.

What's next for Yadier Molina at the plate? Honestly, I do not know. What I do know is that he is not getting any younger, and while he is "expected to be ready for 2016 spring training," "ready" is an inherently vague term. Of course, Molina will still be invaluable to the ball club through defense, pitch calling, and leadership. But, at the same time, I am not necessarily ready to watch Yadi "Singles Hitter" Molina just yet. Yet, if late 2014 and all of 2015 are any indication, I may have no choice.

Credit to BaseballSavant.com and BrooksBaseball.net for data used in this post as well as infogr.am for being such a user-friendly chart-making product.