Stick with me here, and let's take a look back at Joe Mauer over the past two seasons.
To start the 2016 campaign, Joe played in all 24 of the Twins games. He started 23 of those, while playing eight innings during an extra inning contest against the Nationals in his lone day off. During that timeframe, he slash .321/.453/.440 while ripping five doubles and owning an impressive 20/9 walk to strikeout ratio.
Through the first month, Mauer's .453 on-base percentage paced the big leagues, and it appeared as though he knew the strike zone better than the men behind the dish dictating it to him. He battled through long at bats and forced pitchers to come to him. Looking at the sum of his results, Mauer appeared to be the ideal leadoff hitter for the Twins.
Then the calendar flipped to May. Minnesota has now played 15 contests in the month, and while Mauer has started 13 of them, he played nine innings in relief in one, while pinch hitting in the other. What essentially equated to 39 straight games, Mauer put together a paltry .182/.262/.255 slash line while owning a 16/6 strikeout to walk ratio. His plate vision has almost reversed, while his gap power has been sapped to the tune of a lone double. What's different? Maybe nothing but time.
We've seen this before with Mauer though, and we don't have to go back far. In April 2015, Mauer owned a .318/.392/.412 slash line along with a 14/11 K/BB ratio while starting each of the Twins first 22 games. He followed that up by starting 16 of 17 games in May from the 1st through the 19, and his line during that time dipped to .234/.269/.297 with a 15/3 K/BB ratio. That looks again like fatigue set in for the Twins local product.
In trying to give the theory a little more legs, I looked through Mauer's splits by month a year ago. Following April, his next best month was July. After owning .240 averages in May and June, Mauer's slash line rebounded to .298/.340/.426 during July. His strikeout to walk ratio still wasn't great at 17/6 but it wasn't in line with his ugly May. During July 2015, Mauer was given two days off starting 23 of 25 games. He was also lifted in the 6th inning once.
So, it would seem to appear that at 33 years old, Mauer isn't the same youthful athlete he may have been at 23. Ok, in all fairness though, there's some credibility to the idea that Mauer's second month decline (and longer at times) could be to the fact that he's not giving his body enough rest throughout the season.
Last season, Mauer played in 158 of the Twins 162 games and owned a career worst .265/.338/.380 slash line. Prior to that 158 game career high, Mauer had never played in more than 147 games for the Twins (2012). In his first season as a full time first basemen, Mauer played just 120 games for the Twins, but he did deal with injuries at times. When he was a perennial MVP candidate and All Star from 2006-10, Mauer solidly averaged 134 games a season (split behind catcher and designated hitter).
I'm not sure there's ever a fair way to quantify a guy being over extended for sure, but one thing is certain, Mauer's slide has come as the season has drawn on. He doesn't strike me as a guy who is going to bow out of action, so the responsibility to protect him while also getting the most out of him should fall on his manager. If Mauer takes a day or two off a month, a production boost could be a welcomed by product.
What Mauer did during the opening salvo of the 2016 season was incredibly impressive. His approach, eye, and results were among the best of his career. I want to see that again, and while it may or may not be fatigue related, experimenting to get a guy to cease from slashing .266/.383/.367 is a worthy cause.
