This news from Marc Topkin at the St. Pete Times:
Cruz is a pitcher that's been discussed here on DRB for a long time. Tommy Rancel first mentioned him up as a potential bullpen candidate before the 2010 season, and he covered Cruz again this off-season, advocating him as a good buy low candidate. Although Cruz was injured for the majority of the 2010 season and he's only signed to a minor-league deal, he's a very intriguing pitcher due to one main factor: his strikeouts.
In the past, Juan Cruz has been the definition of a power arm. In 2007 and 2008, he struck out over 12 batters per nine innings while making batters whiff on around 12-15% of his pitches; for comparison, Joaquin Benoit stuck out 11 batters per nine this past season while generating whiffs on 14% of his pitches. Cruz's stuff was electric - a 94 MPH fastball and an 81 MPH slider - but he had a control problem, walking around five batters per nine.
His control wasn't a large issue as long as he was striking out 12 batters per nine, but in 2009 Cruz signed with the Royals and promptly fell apart. His strikeout and whiff rates plummeted to 6.8 K/9 and 9% whiffs, his wildness didn't improve at all, and he finished the season with a 5.72 ERA and a 4.92 FIP. And then in 2010, Cruz only pitched five innings before suffering an arm injury and undergoing shoulder surgery for a cyst.
It's impossible to say whether Cruz still has the dominating stuff that allowed him to strike out so many batters in 2007 and 2008, but the Rays have had good success working with injury prone, wild relievers. Before joining the Rays, Grant Balfour and Joaquin Benoit both had recent injuries and control problems, but the Rays were able to successfully manage both problems for each of them. Will this be the case with Juan Cruz? Only time will tell, but I know I'll be keeping an eye on his progress this season.