I'm kind of surprised by the panicking over Marrero. He is a notoriously streaky hitter, so a slow start isn't out of the norm for him and he will make up for with a few strong weeks sometime this month or next. He has shown plenty of power every year in the minors and has looked great defensively in every game I have seen him in this year at first base (also only has one error so far on the year). To boot, there are only six hitters in the IL that are younger than him (TB and BOS teams have 4 of those players).
and he's not in a great line-up either. you can see how that can affect some stud hitters (like werth @ the big league level).
i think he'll be just fine.