Joe Mauer circa 2016: Just who is this guy?

Kim Klement-USA TODAY Sports

Joe Mauer is in the middle of a quietly good season. His current .280/.381/.412 slash line gives him a wRC+ of 113 right now, or 13% better than the average MLB hitter, but Joe Mauer didn't use to be "better than average," he used to be elite. He used to be one of the best hitters in all of baseball year in and year out. Should we be happy he's hitting well enough to justify a starting spot at 1B or can we afford to be optimistic there's still more in the tank after a hot start?

To remove the mystique around who Mauer might be as a player today, it's necessary to revisit some career altering injury history and see how we've gotten from the expectation of Mauer automatically being in the chase for the AL batting title to wondering whether or not he can hit well enough to justify a roster spot, let alone his frequently maligned contract.

Mauer's been seriously up and down since a significant injury on April 30th of 2010. Mauer later said he jammed his heel running out a ball to first base, and the diagnosis was a bone bruise. A bone bruise is the injury which has kept Nick Burdi sidelined nearly the entire year, but Mauer returned in 7 games. Bone bruises normally take 2-4 months to heal so Mauer returning so quickly is extremely unusual, but it shows the former catcher's competitive side. Compensating for the injury, Mauer dealt with hip, knee and shoulder problems during 2010, and finally re-injured his left knee on September 19th, running to first base. After multiple consultations, off-season knee surgery was finally scheduled for December, but waiting for extra consultations didn't give Mauer proper time to recover and get ready for the 2011 season. Early in the season, after it became apparent he just wasn't himself, the Twins' front office made the public diagnosis, stupidly, "bi-lateral leg weakness." It was much later revealed Mauer simply hadn't recovered from knee surgery, and the Twins had allowed Mauer to risk his health by playing anyway. Mauer received a lot of criticism from angry fans, but it was the questions regarding his work ethic, a direct result of the Twins simply not being forthcoming with his situation, which hurt the most. As if the diagnosis itself wasn't a poor decision on its own, added terrible timing made it even worse as Mauer was in the hospital recovering from a serious virus on the 15 day DL that cost him 15-20lbs of body weight when the infamous diagnosis was made to the public. The Twins' front office failed to consult with the former MVP before the press release about his health and Mauer subsequently called the front office out a bit; unheard of for the soft spoken face of the franchise. Mauer later stated he regretted not being more forthcoming with the public himself about the recovery, but cited competitive advantages as the reason he hadn't previously been more open. The 2011 season begins the decline of expectations for Joe Mauer. Had it not happened, the subsequent excellent 2012-2013 seasons would put Mauer in a very different place in regard to expectations and patience with his performance at the plate today.

Speaking of 2013, it would be utterly remiss of me to overlook the impact of a serious concussion suffered by Mauer in August of 2013. While Mauer did have a mediocre season in 2014, he wasn't forthcoming with how much the concussion symptoms affected his vision, sometimes blurring his sight in both 2014 and 2015. The occasional blurry vision was accompanied with sensitivity to light, especially in 2014, impacting Mauer's ability to pick up the ball in the field and at the plate during day, and even with the bright stadium lights during night games. Curiously, his day game performance was significantly superior in 2014 (.777 OPS day, .698 OPS night), but much worse in 2015 (.670 OPS day, .748 OPS night). In any case, Mauer stated he really didn't communicate his issues with management or coaches.

So here we are today. Hampered by serious injury and health issues in 2011, and the impact of various post concussion symptoms in 2014 and even 2015 which Mauer stated have almost completely subsided for the 2016 season, Mauer started off looking like the former MVP had shockingly returned to vintage form. Just as suddenly as his hot start started analysts talking, Mauer slumped. Bad. After just a couple weeks of slumping, fans were quick to adjust their expectations far downward, but what caused the slump and was it fair to assume it would continue?

The first thing I'd like to do is talk about batting average for balls in play (BABIP) and its potential regression to the mean predictive brother, expected batting average for balls in play (xBABIP). BABIP tells you what the player's batting average is based on balls that player has put into play. Hits divided by plate appearances, less walks, less strike outs and less home runs because those plate appearances don't really put the ball "into play." The MLB league average for BABIP is always close to .300, but individual players vary widely as you'd expect because different hitters put the ball in play in different ways. The biggest influences on BABIP is how the balls are put into play, either line drive, ground ball or fly balls. Oversimplifying things, if an average player hit all line drives, and they never hit a home run, struck out or walked, they would have a batting average of nearly .700, while ground balls would give them an average around .250 and fly balls close around .200. BABIP tells you what actually happened while xBABIP (the various formulas) try to tell you what SHOULD have happened if you remove luck.

Year Line Drive % Grounder % Infield Hit % Fly Ball % HR/FB % Pop Up % xBABIP BABIP
2004 19.80% 45.80% 9.10% 34.40% 18.20% 3.00% 0.347 0.300
2005 24.20% 51.40% 3.20% 24.40% 8.70% 2.90% 0.348 0.322
2006 24.70% 49.60% 3.50% 25.80% 10.80% 1.70% 0.353 0.364
2007 17.90% 54.50% 3.10% 27.60% 7.20% 1.00% 0.322 0.319
2008 22.60% 49.20% 5.00% 28.30% 6.50% 4.30% 0.341 0.342
2009 22.60% 47.80% 3.60% 29.50% 20.40% 1.50% 0.349 0.373
2010 24.20% 46.80% 5.60% 29.00% 6.70% 3.00% 0.351 0.348
2011 23.10% 55.40% 4.20% 21.50% 5.40% 0.00% 0.351 0.319
2012 25.00% 52.60% 3.30% 22.40% 9.70% 1.00% 0.356 0.364
2013 27.70% 46.90% 1.80% 25.40% 12.10% 1.10% 0.362 0.383
2014 27.20% 50.80% 2.70% 21.90% 5.10% 0.00% 0.363 0.342
2015 24.10% 55.70% 4.10% 20.20% 10.30% 4.10% 0.352 0.309
2016 28.70% 50.50% 1.90% 20.80% 13.60% 0.00% 0.370 0.321
Unweighted Career Averages

0.351 0.339

As for Joe Mauer, he's been incredibly consistent in his xBABIP. Over his career, he has an unweighted annual xBABIP of .351, with only one season being more than 20pts away from that average. His actual unweighted annual BABIP is .339, which is only 12pts away from his career xBABIP. Mauer has only 4 full seasons where his actual BABIP and xBABIP differ by more than 25pts. Those seasons are 2005, 2011, 2014 and 2015. The concentration of those unlucky years is a little concerning, but weirder stuff has happened. So the surface, it would seem Mauer's luck the past couple years has been really tough, and that happens over the course of long careers. However, what if it's not just "luck" at work in regard to Mauer underperforming his xBABIP? There's a defensive technique often given credit for taking away hits from Mauer and that's the shift. Thanks to newer data at Fangraphs courtesy of Baseball Info Solutions, we can look at the dreaded shift and how it might be robbing Mauer, who often is criticized for not being good enough to adjust his plan at the plate to "beat the shift."

Year Shift Used % No Shift BABIP Shift BABIP
2010 2.46% 0.357 0.182
2011 1.18% 0.317 0.667
2012 4.70% 0.359 0.524
2013 4.64% 0.398 0.125
2014 10.70% 0.334 0.421
2015 10.64% 0.305 0.380
2016 26.47% 0.338 0.284

As we can see, Mauer basically went whomp, whomp, whomp all over the shift in 2014 and 2015, he's beaten the snot out of the shift throughout his career in general, but he is getting owned by it in 2016. To make its impact greater, he's seeing the shift a crazy 26.47% of the time this year! What does this mean? Well, to be honest, Mauer's probably getting double hosed on luck this year. Throughout his career, Mauer has beaten the shift and he's had an actual BABIP close to his xBABIP, but he's having a very bad year in both categories. Anyway, looking at this data was more in line with attempting to just explain whether or not the shift SHOULD be responsible for the difference between Mauer's BABIP and his xBABIP. Taking the career numbers into consideration, it's probably a fluke the shift has been so effective. In fact, most advanced metric research into the shift has concluded, in general, the shift isn't incredibly successful against MLB hitters, though it may have some impact (we're talking like 10pts of average at best)

Okay, so what about the rest of Mauer? There's nothing to suggest Mauer isn't ready to have a serious regression to the mean.. and that mean would be very positive. The walk rate is there at near career best 13.9%. The strike out rate has declined 3 straight years and sits at a high only for Joe Mauer 15.7%. Mauer's clearly putting the barrel on the ball with a career high 28.7% line drive rate. He's hitting for normal power with an ISO of .132 and 13.6% of his limited fly balls are going over the fence, which is is the 2nd highest full year rate in his career next to his crazy Metrodome fueled explosion of an MVP campaign of 2009. He's not popping the ball up, his hard hit rate is right about career average, and his soft hit rate is just below career average, and certainly better than last year.

MLB and Twins fans all around, if things start ironing themselves out like you'd expect as the sample size grows, we may have the pleasure of witnessing a very run ride for Mauer as the year winds down.

Oh, in case you're wondering how big of an impact the xBABIP adjustment would make, I corrected Mauer's triple slash, assuming the non home run ISO stays the same and his actual BABIP was the same as his xBABIP...

Mauer would be slashing .319/.414/.453 for an OPS of .867 which would rank 32nd in all of MLB qualified hitters or 13th in the American League. No longer truly elite, but still, on average, the best hitter for any given team. I can't imagine the values iron themselves out quite that much, but it wouldn't be a stretch to think Mauer could hit over .300 this year. He may not be as cooked as we'd been led to believe in recent years.