I got the latest rankings done a day later than I wanted, but oh well. The numbers are still from before the second half of the season started. Click on the image to enlarge it:
All the previous rankings can be found here. An explanation of what the bubble sizes and positions mean can be found here. Click "continue reading" for a few thoughts on the rankings.
For as much as talk as there is about all the teams still in the playoff hunt, the league has generally spread out throughout the course of the season. Just looking at this graph, it seems like roughly 2/3 of teams are pretty much out of the running. That would seem to imply that the trade deadline will feature a buyer's market, because there should be more teams trying to sell than buy. However, if there is a perception that most teams are actually buyers, that could warp things.
Still, if I were a team like - oh, I don't know, the Mariners - I would aggressively pursue any potential "sell" deals right now, before other teams decide they are out of the running. The market will only get worse for sellers. The best return a seller is going to get at the trade deadline might be right now, unless a team is certain that they have a unique commodity that teams cannot find in other places.
Lastly, winning does seem to matter. As the Pirates have risen from respectability to playoff dark horse, searches for them have increased. Welcome to relevancy, Pittsburgh. The Nationals also saw a significant increase in the past month, though I wonder how much of that has to do with the peculiar Jim Riggleman situation - though part of what made it so odd was the winning streak he walked out on.