The UFA season is a pretty wild period in the NHL calendar. At that point, players who were loyal to a team suddenly go on the hunt for a better contract somewhere else. Of course, hockey is a business but it seems some guys are more willing to move than others.
Michael Del Zoto has been in Philadelphia for three years now and he did not exactly break the league. Sure, injuries slowed him down a bit, but whom many saw as a highly offense oriented defenseman became more of a regular NHLer. Many fans were disapointed with him in the last two seasons and his new UFA status might give him a fresh start somewhere else. The interest seem strong from other teams too.
His last two year, 7,75M$ deal might be a decent stepping stone for his next one. His performance doesn't command a 5M$+ salary but he's still bringing some positive upsides to a contending team. It will be interesting to see what might unfold in his case.