Three games in a row, even, with the opener replacing DeGrom. But I don't think a 22 year-old needs a "rest" after three games. No, it's not a big deal in and of itself, but having Marsh be the only guy who can play CF if Crawford needs a day off still seems sub-optimal (especially when you add in Kemp's bumpy LF defense). And how does Moore even get into a game? Garcia days off I guess.
As far as the heart of the line-up, if Schwarber and Harper can't hit LHP as well as they have in the past, and you're playing Marsh, that's a problem too. Not actually worried, they aren't going to hit .150 (or worse) forever. Probably more worried that Bohm and Garcia won't do enough to balance out the line-up.
I also don't have a problem with building an offense around home runs, but then you need guys to actually hit home runs.