We actually haven't traded out of the first round as often as is perceived.
I don't really count the trade for Cooks since the classic Belichick draft trade is for a good future pick; in 2017 we essentially drafted Cooks in the first round (and later got the pick back from the Rams).
Other than that the most recent time was in 2013 (which we turned into Collins, Ryan, Boyce and Blount!), and then you have to go back to 2009. So that's only one classic 'trade out of the first round' in 9 years.
If it does happen this year, since we draft at the end of the round, it could just be to move down a few picks, which despite the headline of "Patriots trade out of round 1 again" isn't that big a deal, except in affecting contract length.