Here are a few cornerbacks -- with a round noted for when they could come off the board -- New England could consider in the 2018 NFL Draft.
The Patriots have selected only one cornerback in the first round in the Bill Belichick era (Devin McCourty in 2010). However, Jackson would be a good pick late in the first round, and an even better value early in the second round if Jackson slides to them in Round 2. Jackson wasn't expected to be very fast, and he wasn't -- he ran a 4.56-second 40-yard dash at the NFL Scouting Combine. His quickness and ball skills make him a likely starter in the league, though.
If the Patriots address a different position in the first round, they could pick up Davis with the mid-second round selection they received from San Francisco in the Jimmy Garoppolo trade. Davis is not the most fluid corner in the draft, but his 6-foot-1, 206-pound frame and ability to stick with receivers inside as well as down the sideline give him a chance to quickly earn a starting role.
Jackson plays larger than you would expect at a shade under 5-foot-10, just like Butler did coming out of West Alabama. I expect Jackson will be able to handle himself against NFL receivers despite the lack of height, as he's never backed down from a tussle.