Mayer is a big boy, lot of moving parts for him at shortstop. Not sure we can ever rule out injuries for him.
now third base might be the single best defensive position for him with the added benefit of the chance to mitigate injuries
As for his hitting, he has a little swing and miss in his swing, but other than that, the dude is a tremendous hitter!!!! Definitely further along than the other two!!! He may not have the same ceiling though
bottom line, I think he only sees Fenway if story get hurt or slumps big time. At the end of the year we have to add him to the 40 man roster anyway