At the time of his first demotion, Nava was hitting .149 and had not exactly lit the world on fire down at Pawtucket, hitting .253/.347/.398 there. With the injury to Mike Napoli, it was thought perhaps he could help the team at first base and in the outfield, but in two starts and 11 plate appearances, he only managed one walk and no hits, lowering his average further to .130.
Alex Hassan remains on the roster to provide outfield bench depth, despite only hitting .213 at Pawtucket this year. Hassan is a natural right-handed hitter. Nava is better as lefty hitter, though he can switch-hit.
De La Rosa is making his first major league start since 2011 for the Dodgers who sent him to Boston in the payroll-shedding deal of 2012. As a starter, while he may not hit triple digits as he did as a reliever, you can expect a more finished product than last year.