Got any targets for LF? Melky doesn't actually seem like a bad option if you get him on a 4 year deal. A bit of proven production at the top of the lineup. 13-15M per year, shouldn't be a negative value if he starts at ~2WAR next year.
Russell, Melky, Rizzo, Bryant, Soler, Baez, Alcantara, Montero, Pitcher is a much better lineup
Lester, Arrieta, Hammel, Syndergaard, Hendricks is a pretty slick rotation with lots of depth like you said.