Detroit signed Prince Fielder, who is tied for 30th in the AL with just 26 home runs. But when you think back to the years when he hit 50 and 46 home runs in Milwaukee you also need to think of the years he hit 28 and 32. His average has been consistent throughout the season (months of .330, 315,.305, and .370). His OPS is 9th best in the AL but he's 21st in slugging and not even in the top 40 in WAR (Wins against Replacement).
The Twins grabbed Josh Willingham from the A's for 21 million over three years. He hit .246 with 29 home runs in 2011. Willingham's having his best year yet - 34 home runs - and trails only Miguel Cabrera and Josh Hamilton in runs batted in with 105.
The Orioles got Wei-Yin Chen for $3 million. Though his stats are not all that impressive, he has been an important part of the Orioles' rotation, winning twelve against nine losses and using up lots of innings.
One of the big moves made in the off season was by Tampa Bay, who got Carlos Pena back from the Cubs after he hit 28 homers in 2011 (though he hit just .225). Pena had hit 46, 31, then 39 home runs from 2007 to 2009 with the Devil Rays, but this year he has just 17 and is batting a lowly .194 with 170 strikeouts.
The Rays have fared much better with Fernando Rodney. Though it may not be a shock considering how well closers do in Tampa Bay. They signed him for $2 million even though he had not posted an ERA or FIP (fielding independent pitching) under four since 2007 and last year with the Angles his walk ratio was higher than his strikeout ratio. But eliminating the high leg kick at the start of his delivery seems to have delivered results. This year his strikeout to walk ratio has gone from 0.93 to 5.00. He's saved 43 games (tied for best), his ERA is 0.66, and opponents are hitting just .167.
Hiroki Kuroda, who is earning a cool $10 mill with the Yankees (which probably makes him about average on the team) is 14-10 and among the league leaders (fifth) in WAR. His ERA and WHIP rank seventh in the AL.