Just to backup my post with my personal favorite stat, here is the yards per target breakdown for other players with similarities, since they were lined up on the outside. Let's say a minimum of 20 targets and I left off Ochostinko simply because his problems with the playbook were well-documented, although he did meet the threshold.
Brandon Tate, 2009 (rookie), 46 targets, 9.39 ypt
Randy Moss, 2007, 160 targets, 9.33 ypt
Randy Moss, 2009, 138 targets, 9.16 ypt
Brandon LaFell, 2014, 67 targets, 8.60 ypt
Randy Moss, 2008 (Cassell), 125 targets, 8.06 ypt
Deion Branch, 2011 (age 32), 90 targets, 7.80 ypt
Reche Caldwell, 2006, 103 targets, 7.38 ypt- NOT RE-SIGNED
Brandon Lloyd, 2012, 130 targets, 7.01 ypt- NOT RE-SIGNED
Aaron Dobson, 2013 (rookie), 74 targets, 7.01 ypt- ???
Kenbrell Thompkins (rookie), 2013, 70 targets, 6.66 ypt- CUT EARLY NEXT SEASON
Randy Moss, 2010, 22 targets, 6.31 ypt- TRADED MID-SEASON
Deion Branch, 2012, 29 targets, 5.00 ypt- NOT RE-SIGNED
Brandon Tate (injury), 2010, 0 targets, 0.00 ypt- NOT-RESIGNED
Why did I italicize the bottom half of this list? Because none of the players who were under 7.5 ypt played another full season with the Patriots, except for Dobson who is really playing the season on the bench. You can go deeper into the numbers or point out exceptions and say I am cherry picking, but I think this chart gives a pretty good objective sense of the Patriots player evaluations at this position. It is interesting that Tate performed so well in his rookie season- in fact much better than Dobson- but an injury derailed him. The fact they parted with him so readily, though, may be a cautionary tale for those who think Dobson is destined to make a big comeback. The other thing people overlook is that from year 1 to year 2, players should be making huge strides in learning the complexities of the offense.
My guess is that Dobson's benching is not due to injury, or if it is, it still gives me very little confidence that he will be a valuable player in this offense.