The Sox may be relying on hope for young position players to have break-out seasons: Casas or Duran making an All-Star team, Abreu or Rafaela vying for Rookie of the Year votes, even Teel providing a spark as a late call-up...
Imanaga, Stroman and Wacha (coast-to-coast good the past two years) -- would all fortify the rotation, but probably not supply the starting consistency needed to pace the bullpen and boost the Sox into serious contention. No one goes seven innings anymore, but is it asking too much to just complete six; what now constitutes a quality start?
Spending big on more "elite" starting pitchers may not make sense in the short run, but having the stability of a stopper or two at the top of the rotation establishes a foundation for longterm success. Inspiring your teammates -- who expect to win every time you toe the rubber -- changes the very culture of a dugout, clubhouse and ultimately, the fanbase.