Raiders coach Dennis Allen has his work cut out for him during the offseason. (US Presswire)

The Raiders under rookie coach Dennis Allen and first-year general manager Reggie McKenize touted a "new era of excellence." But after going 4-12, Allen and McKenzie have a clearer picture of exactly how much work needs to be done to turn the Raiders into a playoff team.

Not a single Raider made the Pro Bowl. There are numerous holes to fill on both sides of the ball and on special teams.

Free agents who must be signed: 

OLB Philip Wheeler -- The former Indianapolis Colt had a team-high 150 tackles. He plays with passion and relentless energy. He's exactly the type of player Allen wants on his team.

TE Brandon Myers -- Myers produced a career year in 2012, leading the team in catches with 79 and receiving yards with 806. He became QB Carson Palmer's most dependable target. Myers lacks deep speed and ultimately would be better suited as a No. 2 tight end. Either way, he's worth keeping.

DT Desmond Bryant -- Bryant, who initially signed with the Raiders as an undrafted rookie from Harvard, had one sack in each of the final four games and tied DE Lamarr Houston for the team lead with four. He can play inside or out and adds valuable depth.

Positions needing improvement: 

Cornerback -- No other position is in greater need of an upgrade. Michael Huff, a career free safety, was forced to start the final 14 games at left corner after starting corners Ron Bartell and Shawntae Spencer were injured early in the season. In the final game, Brandian Ross -- signed off of Green Bay's practice squad early in the season -- made his first career start at right corner.

Defensive end -- The Raiders desperately need an edge pass rusher, someone who can put consistent heat on opposing quarterbacks. The fact that no Raider had more than four sacks tells you how bad the problem is.

Offensive line -- Fired offensive coordinator Greg Knapp took tons of heat for installing a zone blocking scheme that never seemed to click. But the Raiders' problems up front go beyond scheme. They need an infusion of talent on the offensive line, players who can open running lanes no matter what system is used.

Wide receiver -- The Raiders have plenty of young wide receivers suited for complementary roles but no true No. 1 receiver. This is a longstanding problem that needs to be fixed. Neither Darrius Heyward-Bey nor Denarius Moore has proven to be the solution.

Follow Raiders reporter Eric Gilmore on Twitter @CBSRaiders.