As I return from vacation, let's take a look at two potential summer-long storylines that have developed for the San Francisco 49ers -- the contract situations of standout guard Alex Boone and Pro Bowl tight end Vernon Davis.Both players, who are each dissatisfied with their contracts, have stayed away from the voluntary portion of the team's offseason program. The 49ers can fine each player if they stay away from the team's mandatory minicamp, which will be held June 17-19.