Felix Doubront’s spring is already off to a rather rough start, which isn’t too encouraging considering the lefty wore down during the second half of last season. Doubront will be entering his second full season in the bigs, as he figures to be Boston’s No. 5 starter to begin the year. The hope is that he’ll be more like the pitcher who went 9-4 with a 4.41 ERA during the first half of last season than like the hurler who went 2-6 with a 5.54 ERA in 12 second-half starts. Manager John Farrell has already stated that Doubront will be held back a little bit during the early stages of spring training, though, because of weakness in his throwing shoulder. That’ll definitely be something to monitor, not only because of what it means for his future, but also because any missed time could pave the way for guys like Franklin Morales, Rubby De La Rosa and Allen Webster to hop into the starting mix.