One of the 49ers’ biggest needs heading into the NFL Draft is cornerback.

They have two good ones — Charvarius Ward and Deommodore Lenoir — who both will be free agents next year. And they don’t have a good no. 3 cornerback. Last year, they had to sign a retired Logan Ryan off a cruise ship midseason to play corner for them in their nickel defense, and he gave up the game-losing touchdown catch in the Super Bowl. Now he’s retired again, and the 49ers’ don’t have a clear-cut no. 3 corner.

They have Isaac Yiadom, Ambry Thomas, Samuel Womack and Darrell Luter Jr. — four guys who will compete for the job. It’s possible none are good enough to hold it down. Which means the 49ers certainly should consider drafting a cornerback as early as Round 1.

But since Kyle Shanahan became the head coach in 2017, the 49ers never have drafted a cornerback before Round 3, and they’ve taken only two corners before Round 5 — Thomas and Ahkello Witherspoon. Neither player panned for the 49ers, although Witherspoon had a good season last year for the Rams.

The 49ers want to play mostly zone coverage, so they don’t value cornerbacks. They don’t ask them to do much. That’s why they’ve drafted so many corners in Round 5 or later: Luter, Womack, Tariq Castro-Fields, Lenoir, Tim Harris and D.J. Reed.

When the 49ers want a corner who can play man-to-man coverage, they tend to draft that player in Round 3. But new defensive coordinator Nick Sorensen comes from zone-coverage background, and so does assistant head coach Brandon Staley, so don’t expect the 49ers to change their tendencies this year.