Becuase they were ready to commit long term.
According to Ryan Lawrence, the Phillies and the former All-Star second baseman agreed on a three year contract extension which will keep Sandberg at the helm of the Phillies ship until 2017, though, the final year is a club option.
Sandberg signed a three-year contract through 2016 with a club option for 2017.
Sandberg has worked his way up through the minor league system and has long been favored to become a manager, it was just a matter of time.
The injury riddled Phillies have a winning record with Sandberg at the helm, after he took over for the fired Charlie Manuel and the former Chicago Cubs great should emerge as one of the premier managers in baseball over the next few seasons.
Of course, cleaning out some of the aging Phillies roster would be a help.