It's go time for major league general managers. This is the time they shine and broker deals that could make or break a team's season, or set in motion its offseason. But certain GMs are under more pressure to make deals than others. Who's under the most pressure? Let's take the temperature of the following GMs and see just how critical it will be for them to get something done.

1. Ruben Amaro Jr. | Philadelphia Phillies

There hasn't been a GM under this much pressure to make multiple deadline deals in a decade.