Essentially, the Pats are protecting their WRs because many teams have issues at this position right now and they think they may be able to get some trade value for them. Kyle Dugger is also in a similar boat. Conversely, there's not as big of a clamoring for interior linemen and the ones NE cut weren't that hot anyway. Once waiver claims process and teams see if they did or did not get the guys they claimed, those teams who did not have a successful claim will be more likely to raise their bid in a trade for a player from NE.
Additionally, NE may get some successful waiver claims themselves which will create a need to cut the same number of players in return.