Players jump from AA to the majors all the time. I seriously doubt Castillo is blocking anyone, since we have no ML ready or near ML ready OF prospects in our system.
Craig and Dominguez are not the reason Devers is still in AA.
I'm not sure about roster limits at the AAA level, but at this time, I do not think C & C are "blocking" anyone's progress. Maybe someday they might.
Maybe DD still thinks there's a slight chance one of these guys will get their act together and force their way onto the team again. Very very doubtful, but at least these guys provide some entertainment to the Pawtucket fans.
On another note: according to soxprospects.com our highest ranking prospect in AAA is #15 Jalen Beeks. (17 Ben Taylor, 18 Tavarez, 19 Callahan).
How about AA? 1 Devers, 6 Lakins, 7 Chavis -just promoted, 10 Longhi.
That's just 8 of our top 20 prospects at the upper levels on the farm. If anything, we lack top talent at the upper levels, so I can't see veteran blockage as being an issue.