The Giants traded Ramon Ramirez and Andres Torres to the Mets for Angel Pagan.
Ramon Ramirez had a .8 WAR in 2011, and a WAR average of 1.2 in the past 3 years. He is arbitration eligible this offseason, so his salary for 2012 is not updated. However, WAR suggests he is worth 3.6 million according to the Halladay Standard (he made just over 1 million in 2011).
Andres Torres had a 1.3 WAR in 2011, and a WAR average of 2.57 over the past 3 years. He is also arbitration eligible, who made 2.2 million in 2011. According to the Halladay Standard, he is worth 7.7 million, which is certainly more than he will receive in 2011.
Angel Pagan on the other hand, had a .2 WAR in 2011, and a WAR average 2.87 over the past 3 years. He made 3.5 million in 2011, and is arbitration eligible for 2012. He is worth about 8 million according to the Halladay Standard.
So just according to WAR (and salary), the Mets seem to have won this trade.