I'd let Garcia go for Nava at this point. I think the chances of him passing through waivers and being re-signed to a minor deal are pretty high. And we are talking about a 30-year-old bullpen arm who is one year removed from one decent season. He put up good numbers at AAA last year, but we aren't talking about Mariano Rivera in his prime here, we are talking Luis Garcia. I certainly would have kept Ascher over him.
My concern with keeping Valentin is two-fold. 1. He hit .248 in only 30 some games last year at AAA. I don't see that transferring to great success as a utility guy at the Major League level, at least not right away. 2. Sometime this year, or this time next year, the Phillies could have Hernandez, Kingery, Glavis, Valentin and Crawford for two spots. I see a trade coming sooner rather than later and if Valentin is going to be that guy, let him put up solid numbers at AAA. Or if the Phillies see him as the next Blanco, then let him play that role at LeHigh Valley this year.
and Nava doesn't strike out much at all - not saying Valentin or Stassi are destined to strike out, but I see Nava has having better success off the bench then Valentin.
Just my two cents