I see how you're not doing well, but you have the foundation of a good team. I wouldn't stand pat, but I wouldn't panic either. I would absolutely pick up Upton over Anderson. A fourth outfielder with upside could really do you some good, especially if you follow him closely and match him up in situations where he figures to do well. I do think Holliday will bounce back and give you a solid if not spectacular OPS, but he won't be a 30 HR guy.
Otherwise, just look for a decent supplemental middle infielder. Your pitching will come back and be okay over the long haul, but you just need to be aggressive with available hitters that have the upside to outperform one of your starters. In particular, pay attention to youngsters and prospects that may get a surprise callup. You don't really need veteran stability, you need to take gambles that may pay off big. You have enough to keep you within the realm of competitive, but you also probably don't have enough to make up enough ground as is. Put a little bit more risk and reward on your bench though, and you could be in great shape.