Beginning with the Giants, it's clear that they have been decimated by injuries on the offensive side of the ball. With both Buster Posey and Freddy Sanchez possibly out for the year, San Francisco needs to pick up another bat for the middle of the order.
This upgrade does not have to be significant, but an experienced shortstop or second baseman would make a huge difference for the Giants as the summer truly begins. SF should take a good look at either Dodgers SS/2B Jamey Carroll or Astros SS Clint Barmes. Also, they should find a veteran catcher who can step in and play immediately. Someone like Bengie Molina comes to mind.
Since the Giants have such an incredible pitching situation, they only have to upgrade at the plate. Ironically, the Diamondbacks are just the opposite.
I'm not talking about picking up a new closer or a setup man, as those positions are held down nicely by J.J. Putz, David Hernandez, Joe Paterson and Esmerling Vasquez. What the Diamondbacks need is a solid innings eater and a middle relief guy.
Aaron Heilman and his 7.50 ERA just aren't cutting it anymore. A little more bullpen depth, and magically the Diamondbacks become a better team.
Also, if a good starting pitcher can be had for a reasonable price, it should be taken into consideration. Someone on the level of a Jon Garland (ironic, I know) could help from the 5th starting spot.
In the end, the Diamondbacks just need to play better against the Giants -- after losing tonight, they are 1-5 against San Francisco in 2011.