Rubby De La Rosa is going to be 24 years old during the 2013 season. Tommy John surgery performed in August of 2011 means that his arm hasn't developed in the same way that of your typical 24-year-old hurler with major-league experience would have. What should have been a normal developmental increase in innings from 2010 to 2011 instead found De La Rosa about 10 innings short of his new career-high of 110, and with 2012 spent in recovery, he logged just 13 frames between the minors and majors.
For 2013, this means the Red Sox won't be able to just throw him out there as a depth option from day one. According to Alex Speier of WEEI, they'll take things more slowly than that in order to build him back up:
What does that mean? The Sox are unlikely to use De La Rosa during spring training in stints of more than two innings. The team will likely maintain innings restrictions on him early in the season, and then slowly build up the length of his outings towards the middle of the year. There's no hard and fast innings target for the right-hander for the season, though certainly, if he could build on his prior career-high of 110 innings - perhaps by moving up to 120 or 130 frames - that would represent a player development success in the eyes of the organization.
As Speier says, 130 frames or so would be a natural progression in his development, as if the missed time never happened and De La Rosa was still working to best his career-high of 110 innings. Rather than limit him all year, though, Boston will start him slowly with shorter stints in the spring and at Triple-A Pawtucket, gradually adding longer outings on top of that. By the time the Red Sox might need him in the rotation in the latter portions of the season -- say if multiple starters have gone down, or Franklin Morales is unavailable to spot start -- then De La Rosa should be up to the task. Early on, though, you're more likely to see someone like Steven Wright get a shot after or in place of Morales.
That's how things with young pitchers work. Felix Doubront's first full year in the majors brought an increase of over 30 innings from his career-high, but that put him at just 161. Matt Barnes threw just under 120 frames as a 22-year-old in his first full year as a professional. Allen Webster has been driven a little harder, putting up 145 frames in 2011 as a 21-year-old, but even that's not a massive sum, and it represented just a 14-inning increase from the previous campaign.