Buy, hold or sell?

The trading deadline is less than three weeks away, and there's not much separation in the NL standings -- about 10 teams still can call themselves contenders without eliciting derisive laughter. Below we will review the needs of each contending club heading into the trading deadline, although it's important to recognize that even the most active club typically addresses only one or two holes, and this year's trade market is not a promising one for major additions.

Note: Any references to games behind refer to the loss column, which is the only games behind figure that matters (and is what's used to calculate a magic number).