Andrew Bailey has a 7.2 WAR over his 3 year career, a 2.4 WAR average. He will be in his first year of arbitration in 2011. He has a sparkling -4.096 PE and -3.426 adjusted PE. He has a spectacular TR of 13.52, and FIP - of 67. So for the past 3 years, Andrew Bailey has been one of the elite relief pitchers in the game. There is some cause for concern though. It seems there has been some regression. In 09 he had a WAR of 3.9, then a 2.4 in 10, and just a .9 in 2009. His PE was -2.37 in 2011, -2.75 Adjusted, and a FIP - of 73, and a SIERA of 2.99. These numbers are hard to complain about, and as long as the regression doesn't continue, they are still really good. There is also the point of small sample sizes, he pitched just over 40 innings in both 2010 and 2011.
Ryan Sweeney had a .8 WAR in 2011, with a 1.53 WAR average over the past 3 years. He is also arbitration eligible. In his career, he has a 1.5 D-WAR, with an above average Range Factor and Fielding Percentage. He did struggle in 2011, costing his team 3-5 runs above average. Offensively, he has a .342 OBP, 1.746 O4S, 95 OPS +, .196 Secondary Average, and .096 ISO. He has 4.5 Runs Created per Game and a .461 Offensive Winning Percentage. He made 1.4 million dollars in 2011.
Josh Reddick has a 1.9 WAR in 403 PA, not quite a full season. Adjusted for 600 PA, it is a 2.86 WAR. He isn't arbitration eligible yet, so he will make around half a million dollars in 2012. While proving to be an excellent defender, his offensive statistics are very poor so far. He has an O4S of 1.576, OPS + of 86, and .464 Offensive Winning Percentage. However, he has better Secondary Average and ISOs then Sweeney, at .227 and .168. This certainly gives you hope (along with his WAR projection) that he will be better than Sweeney. On the other hand, his AAA statistics are very unimpressive in over a full season of work, with just a .748 OPS, projecting to a poor .682 OPS in MLB.
Miles Head has never been above A ball, and has decent but not over impressive statistics at a .351 OBP, 1.85 O4S, and .172 ISO. He does walk almost 10 percent of the time. At first base, he is about average, perhaps a little bit better according to Range Factor.
Raul Alcantara is a similar story, he hasn't played above A-ball, but he is a starting pitcher. In 26 starts, he has an unspectacular .0369 PE, although his FIP is lower than his ERA. But even if his PE is an even 0, that doesn't translate well, and his lack of strikeouts (6 K/9IP) is concerning. However, his ERA is nice, and his K/BB ratio is a very very good 4.2. He is just a contact pitcher. Some have been very successful, and he can be if his HR/9IP stays at .1.
I give the nod to the Red Sox in this trade, it appears that Reddick is the best player in the trade according to WAR, but his poor offense concerns me for the A's. Sweeney is almost certainly a downgrade (especially with declining defense) from Reddick, but they add Bailey, who is a (although declining) solid closer. Although prospect gurus seem to like Alcantara and Head, their numbers make it hard for me to fall in love with them. Of course, who wins the trade will depend on how they do, but I still think the Sox have a slight edge.