As the Raiders gather Monday for their first day of the team’s official offseason workout program, they’ve already added several new faces.

Through free agency, general manager Reggie McKenzie has brought in cornerback Sean Smith and safety Reggie Nelson to strengthen the secondary, versatile outside linebacker Bruce Irvin and elite guard Kelechi Osemele.

But the Raiders still have needs, though not as pronounced as at the end of their 2015 season that ended with a 7-9 record under first-year head coach Jack Del Rio.

So what are Oakland’s biggest draft needs now?

Here are five positions that could be addressed with the team’s No. 1 pick, the 14th overall selection, on April 28:

Cornerback – Even with Smith and holdover David Amerson (who’s coming off the best season of his career), the Raiders are vulnerable at the position should an injury occur or Amerson revert to previous form. Former first-round pick DJ Hayden has yet to make a major impact and TJ Carrie was flipped between safety and corner in 2015 and needs to find a home.

Interior defensive line – The Raiders actually have plenty of talent up front, with Justin Ellis, Dan Williams and Stacy McGee, but as Paul Gutierrez of ESPN.com noted recently, “adding another run-stuffer to the interior defensive line … early might be the best call of all.”

Middle linebacker – Ben Heeney was a great find in the 2015 draft and is penciled in as the starter for 2016. Still, if a talented player such as Alabama’s Reggie Ragland is available when Oakland picks, it would be hard to pass on a player who figures to have even more upside than Heeney.

Running back – Again, the Raiders already have a strong starter at this spot with Latavius Murray. But the backup cast – Taiwan Jones, Roy Helu – doesn’t really have every-down capability. Another big, explosive back would give the Raiders more depth and options and help keep Murray fresh.

Offensive tackle – With Donald Penn on the left side and either Austin Howard or Menelik Watson on the right side, the Raiders already are strong at the position. But if one of the best tackles in the draft is still on the board when McKenzie picks, it might be a good decision to bring in another top talent who could eventually succeed Penn in two years or challenge Howard and Watson.

One thing is certain: After all his work in free agency, McKenzie now has some flexibility to go after the best player available when it's his turn to pick, while not having to worry about filling one or two very specific weak areas.