The 2013 Augusta roster had a stellar starting pitching rotation and a well above average bullpen. They used that dominant pitching to overcome what was a decidedly below average position player contingent and earn a spot in postseason play. So, assuming the typical 1-level promotion schedule, it should come as little surprise that San Jose should have another typically strong pitching staff on OD 2014. It should also not be surprising if several of the more advanced position players that the Giants signed after the June draft in 2013 (and who got their feet wet in short-season ball play) get promoted ahead of several of the 2013 Augusta starting position players to earn a spot on the 2014 San Jose OD roster.
The active roster limit in A Ball leagues is 25 players, so keep your list to that limit. If you want to include an "extended roster/taxi squad" item with players that you think will populate the remaining Reserve List spots in your predictions then you can include up to 10 other players (the Active + Reserve List limit for A leagues is 35 - which also includes all players on the 7-Day DL). The Giants almost always go with a 6 man starting pitching rotation in San Jose, although you can make it 5 if that's your prediction. Add in the 9 starting position players (including the DH - who often gets a few starts in the field during a given week) and a minimum 2 man bench (backup catcher + backup IF) and that brings you to 17 players. Then you have to decide if you want an 8 man bullpen or a 7 man pen + a 3rd bench player.
Here's a template that you can cut & paste to use for your own predictions (add or subtract an SP or RP to fit your needs):
On the extended roster (Reserve List):