The Athletics traded Gio Gonzalez to the Washington Nations for A.J. Cole, Brad Peacock, Derek Norris, and Tom Milone. Gio had a 5 WAR in 2011 (despite making just $420,000) and a 4.6 WAR average in his 2 full seasons. His career PE is -.86, with an adjusted PE of -.73. However, his career FIP - is average at 100, and his SIERA is 4.05, hardly impressive. His TR was similarly unimpressive at 8.74. In fact, the only really good thing you can say about Gio is that he has a very good strikeout rate for a starter. Other than that, he seems pretty average.
Cole has never pitched above A ball, but was phenomenal there, earning a -3.16 PE as a starter. To give you an idea of just how good that was, in the league he pitched in (the South Atlantic League), the average PE was .281. Even better was his adjusted PE at -4.63. He didn't walk many batters and he didn't give up many homers either. Even better, he is just 19, when the average pitcher in the league was 22. He is certainly AA ready.
Peacock has 9 AAA starts under his belt, and earned a -2.54 PE. This projects to about an even 0 PE in the Majors, pretty good for a starter. However, his adjusted PE is a full run higher, meaning he would adjust to a 1 PE, which would be solid but nothing special. However, since it is only 9 starts, it makes sense to look at his AA numbers as well. There (mostly as a starter) he registered a -4.7 PE. Even though we don't yet have a pitcher's AA metric, we can assume that a regression for a pitcher from AA to AAA would be very similar to a hitters. According to Simple WAR, hitters put up just 67.7% of the numbers in AAA than they do in AA. This would lower Peacock's PE to -3.18, better than he actually pitched in his 9 starts in AAA. This would adjust to a -.65 Major League PE, almost as good as Gio.
Norris spent 2011 in AA, playing in 104 games. There he had a .367 OBP, .813 OPS, 2.4 PAPP, 1.48 PPG, adding up to a 3 Simple WAR. This means that already, at age 22, he projects to be a .64 O-WAR player. This is while being a catcher who throws out 40% of base runners, and an above average range factor. It is not crazy to believe that he could already step into the Majors and put up a 2 WAR if given enough playing time.
Milone spent 2011 in AAA, posting a -2.75 PE as a starter. This projects to a -.22 PE in the Majors. In 2010, he spent the year in AA, and had a PE of -2.2. This obviously doesn't project near as well.There are a couple ways to explain it, he could have improved, and his FIP is better than his ERA in both AA and AAA. For what it is worth, the Bill James projections have him earning a very nice -1.22 PE.
I think it is pretty obvious that the Athletics won this trade. Even though Gio is a decent starter with a low salary, the A's got 4 players who project to be good in the Majors.