The Biggest Reasons Behind Joe Mauer's Struggles

Heading into the 2014 season, Joe Mauer was the active career leader in batting average at .3230. Now, 74 games into the season, that average has dipped all the way down to .3192, and Mauer has lost his stranglehold on the top spot with Miguel Cabrera holding the honor.

Not a lot has gone right for Mauer in his first season from out behind the plate. The neo-first baseman has limped to a .261/.334/.338 slash with a .298 weighted on-base average (wOBA). To say this season has been a nightmare for the six-time All-Star and 2008 MVP might be a wee bit of an understatement.

Right now, Mauer holds a -0.58 nERD, a numberFire-specific stat that measures how many runs below or above average a player is worth to his team if they were to record 27 plate appearances in a game. That means that Mauer is actually losing runs for the Twins in comparison to an average player. Mauer has never had a nERD lower than 0.43 in a season in which he has recorded at least 500 plate appearances, and he usually sits between 1.5 and 2.5. Part of this is his move to first base killing his nERD value, but he also has just straight struggled.

The question for Mauer - and everyone in the Twins' clubhouse - is why is this happening? Is he drained from being surrounded by too much cute in his twin daughters? Is his head too itchy? Or is he just still trying to thaw from yet another delightful Minnesota winter? Let's try to find out.

Swing Away, Merrill

While I can't check Mauer's scalp (although I'd love to run my nose through that delectable dander), we can look at his swing rates. While the rest of the team has basically stopped hacking, Mauer's trend is going the opposite direction.

In the table below, o-swing percentage refers to the percentage of times Mauer swings at a pitch outside of the strike zone. Z-swing percentage is the same thing, except at pitches within the zone. Swing percentage is the percentage of swings on all pitches that a batter sees.

As you can see, Mauer's letting it loose this season. Unfortunately for him, it's not paying off. His 18.0 strikeout percentage is the highest in his career, and only his second total above 13.7 percent (the other was 17.5 percent last year). On the flip side, his 10.0 walk percentage is the lowest of his career; he has never been below 11.1 percent in a full season.

It's not as if Mauer is swinging and missing a ridiculous amount more, either. Last year, his contact rate was at 83.8. It's up to 85.4 percent this year. Granted, both of those totals are significantly lower than his 91.1 total in 2010, but that was basically ridonculous, so these are still decent tallies.

All of this isn't too say that Mauer has suddenly become a reckless, disheveled vagabond trying to whack his way out of a slump. His 39.7 swing percentage is still the 19th lowest of all qualified players in the league. It's just a significant hike from the Mauer of old that was winning batting titles left and right.

Worm-Burning Galore

The changes for Mauer aren't just with his swing rate. Even when he makes contact, things aren't going as they used to. The chart below shows some of Mauer's batted-ball data from the past two seasons. Basically, ball don't fly for Mauer anymore.

All of the above has resulted in a .318 batting average on balls-in-play (BABIP) this season compared to his .383 mark last year. Now, granted, it shouldn't have been expected that Mauer would keep his BABIP as high as that, it shouldn't be as low as it is now. His line-drive percentage is the fourth best in the entire league, and yet his BABIP is very average.

The other thing that jumps out of the page here is how few balls Mauer is lofting. His fly-ball percentage is the seventh lowest in the entire league, putting him among the Dee Gordon's and Elvis Andrus' of the world. This, combined with Mauer's career-low home run to fly ball ratio of 4.7 percent, is why he has only hit two home runs this year with none since May 3rd.

Lady Luck Has Her Say

I had mentioned earlier that it was strange to see Mauer's BABIP shoot down so far despite a maintained awesome line-drive percentage. Part of the reason this is happening is that Mauer can't seem to catch a break.

The chart below shows how Mauer has fared based on the trajectory of the balls he has hit this year. The first half of the slash shows his batting average with the second half as his slugging percentage. I've omitted on-base percentage from this because it obviously means less when he's putting the ball in play with each of these outcomes.

The regression in each of the categories can help explain the huge dip in Mauer's BABIP. Considering the league batting average on line drives is .714, it should be expected that, at the very least, that category should spike up. If Mauer has truly taken a step back in the power department, it's possible that his fly ball numbers may stay where they're at. The league average in that category is .132.

Obviously some of the drop-offs in these categories may be permanent due to a drop in actual production from Mauer. However, I don't think all of it is. The man can still hit the baseball. A man with hair like his can't just fall off as quickly as he has. While Mauer may never return to the ball-slangin', wall-bangin' champ of the past, I wouldn't count him out for a serious second-half rebound this season.