In a recent discussion with the media, San Francisco Giants president of baseball operations Farhan Zaidi suggested the team would be targeting prospects close to the major league level in their deadline deals.
If that is indeed the path they choose to take it limits the pool of prospects they will be willing to consider. In order for a contender to be willing to part with talent close to the big-league level, they have to believe that player is not capable of making an impact in the short-term. That could be true for a couple of reasons.