The immediate and shortest response is that the time has not yet come.
Sure, each of the past two seasons, Mauer's numbers have gone in the wrong direction. After batting a career worst .277/.361/.371 in 2014, Joe followed it up with an even worse .265/.338/.380 slash line last season. Although he hit double-digit home runs (10) after just four in 2014, his performance was largely buoyed by timely hitting in situations with runners in scoring position. His two year splits aren't good, and neither is the trend he's currently following.
That said, there's absolutely reason for hope. There's little room to argue that Mauer's production has been sapped by anything other than significant brain trauma. Despite the documented concussions that he's had to deal with behind the plate, the beating he took playing catcher also did him no favors. Although Mauer has since moved to first based, he's noted that vision issues have continued to persist, and no doubt, his athletic ability has decreased to a certain extent.
A season ago, Mauer played in 158 of 162 games for the Twins. As he further distances himself from the serious concussion issues he's dealt with, there's hope that his abilities begin to either somewhat return, or diminish at a slower pace. Following up a season in which he played the most games in his career, the Twins can only hope that 2016 is the next step in that turned corner.
Going into the year, Steamer projections have Mauer slated for a .274/.355/.390 slash line. He's projected to come in just under double-digit home runs (with 9) and see a slight dip in RBI (63). Mauer has always been more of a doubles hitter, and the projections see him nearing 30 (28) again in 2016. After posting a 0.3 fWAR in 2015, the expectation is that he improves by a full win (1.3). In total, that's production the Twins could absolutely be happy with.
Looking at where Mauer tops out at, age begins to become as much of a question as does the previous injury concerns. This being Mauer's age 33 season, it's probably now or never for the turnaround. A few days ago on Twitter, I offered the opinion that Mauer has a chance to hit .300 in 2016, but if he doesn't he won't ever again. That seems like a pretty fair assessment, and a relative summary of where I believe Mauer's career to be at.
While he is not old, he's also not young by baseball's standards. His previous brain injuries have taken the best parts of his game from him, and if we don't see a resurgence now, we likely never will. At this point, it's in the Twins best interest to find out if that resurgence is coming. Regardless of the fact that Mauer will never hit like a true first basemen, being a 1.0+ fWAR player still puts him in the asset category to manager Paul Molitor.
Minnesota shuffled positions this offseason in moving Miguel Sano to the outfield and bringing in Byung Ho Park. As things stand today, having Trevor Plouffe, Sano, Park, and Mauer all in the lineup gives the Twins the best chance to win. Should the summer months roll around and Mauer have regressed even further, the argument could begin to be made to look at other options. For now however, that shouldn't be the case.
If you want to move mauer down in the lineup (and I would), it makes sense. Asking him to be a replacement player at this point is jumping the gun however. His production has to be tied to logical expectations of what he is both capable of and helps the Twins, not what is deemed acceptable for the position he plays
When the dust settles on the 2016 Major League Baseball season, the Twins should have a pretty clear picture of where they can go with Joe Mauer. The season ahead is one that needs to play out for that picture to reveal itself however. Making assumptions or decisions based upon what has happened in his first two years at a new position is too knee jerk for me. Let the year ahead play out, and then begin to talk through the hard realities that may lie ahead.
