The clock is down to the final few ticks for Jake Arrieta and other unsigned free-agent starting pitchers hoping to find new teams in time to be ready for an opening rotation. Once they sign, these free agents still need spring starts, underscoring Cubs president Theo Epstein’s remarks last month about the importance of getting Yu Darvish’s long-term contract done before the start of Cubs camp. Darvish, who makes his Cubs debut Tuesday against his old Dodgers teammates at Sloan Park in Mesa, signed his six-year, $126 million deal with barely a day to spare before camp opened. “The six weeks [of spring training] is really important, especially for the pitcher,” manager Joe Maddon said. “I think the length of spring training is designed for the pitcher. Hitters can get their number of at-bats in a shorter amount of time, but I don’t think pitchers can be rushed.