If Castillo shows that he can play RF better than Craig or Nava, then I would start Ramirez/Betts/Castillo. If Castillo's fielding is (nearly) on a par with Victorino's, then the latter is expendable; however, his health issues and age make it difficult to get much back for him.
Craig has more versatility among the group as he has played all three OF positions plus 1B/2B/3B (although his total games at CF/2B/3B are quite limited). If his batting bounces back, he has the most power of the three but he is not an especially good OF (particularly in RF). Would he be willing to be a bench player? Does he need to play every day to keep his bat up to par?
The main thing goings for Nava is that he is a left-handed bat, he can fill in at first, he is inexpensive, and he is accustomed to coming off the bench.
Ideally, they would have someone young, fast and capable of playing CF on the bench, and a switch hitter wouldn't be bad. But what would they do if there were a long-time injury to their starting CF or RF? Is there a replacement at Triple A?
The bench spots must include a catcher, a first baseman, a middle infielder, a third baseman, and an OF capable of playing CF/RF. Also, you want someone with a bit of power, someone who can get a hit, steal a base, left- and right-handed bats. Obviously, one player can fulfill multiple spots; Brock Holt. Frankly, Quintin Berry strikes as the type of bench OF they need but I wouldn't expect that to happen unless Craig was also part of the bench. Hanigan/Berry/Craig/and the best bat they can find?