I honestly think after this season the Twins should trade Revere at his high point, the return won't be as great but I worry about Revere's ability to continue to hit above .310 moving forward.
If he dips down to the .275 range he suddenly becomes a rather weak link in a persons lineup. Though having his speed in the lineup is nice as well, plus he is super cheap.
In regards to Span, it should be noted that for the most part there weren't exactly a ton of top prospects that were traded this trade season, the package for Grienke wasn't awful, but only had one real nice player and even he isn't that special. Guys that were rated high prior to 2012 like Cox and Turner were traded, but both have lost a bit of value with medicore 2012 campaigns.
I'm not sure if its the new FA compensation plan or the fact that teams are now capped in the draft, but teams seem to be holding onto there prospects much tighter this year.