For forecasting purposes, I tend to give any player a pass for one outlier season, in either direction. But two consecutive seasons set a new level of expectation for me. If Joe bounces back merely to his 2014 level of production, amounting to above league-average OPS, it will be difficult to say he's not an everyday player. It just won't be what we had come to expect from the man. There is nothing that says a player at a particular defensive position has to have certain offensive characteristics. It's simply that a team needs a balance of performance, getting guys on base and then driving them in, and power is easiest to obtain from hulking guys who are limited defensively to 1B or a corner outfield position. If somehow an up the middle position, such as our second baseman currently, provides above average power, you can more easily accept elite OBP from first base, if indeed that's what is produced. But Dozier isn't going to hit 40 homers, and such a number will have to come from Sano and maaaaaaybe Park. The concussion is the easiest explanation for the loss of ability at the plate. It's a brain injury, and like any injury, sometimes the patient heals completely, and other times the healing is less than 100% and ability is degraded permanently. It is quite plausible that Mauer's elite hand-eye coordination has been degraded to the level of ordinary folks like you and me, and it's only his experience and ongoing work habits that allow him to still hit as well as he does. But because the brain is harder to diagnose and monitor than a torn ACL or broken bone, the optimist isn't without grounds to hope for some kind of miraculous bounce-back to his former .300-hitting level. Conversely, age and further wear-and-tear will continue to take its toll on any player, and you can't rule out further decline in 2016 and for the rest of his time with the Twins.