Keep in mind, this isn't necessarily the very best at every position. These are the best players at each position who fit the Raiders team as well as perhaps their budget. They are not in order from best to worst but rather grouped by position.
Fred Davis had his breakout season two years ago when he had 796 yards receiving for the Redskins. Unfortunately, last season, he tore an Achilles tendon midway through the year after playing in a more run- heavy offense leading to less receiving opportunities. He is still just hitting his prime and there is no reason he can't recover and get back the form he had in 2011. But he will have to prove it which means he could be affordable to a team like the Raiders.
WR David Nelson, 26, Bills
At 6-5, 217, he makes for a nice big target for any quarterback. He is sneaking under the radar at the moment because he spent nearly the entire 2012 season on injured reserve from a torn ACL. In 2011 Nelson emerged as one of the leading slot receivers in the league finishing seventh overall in terms of slot yardage and added three touchdowns.
OT Eric Winston, 29, Chiefs
The 5-year stalwart starting tackle shored up the Chiefs glaring Right Tackle issues last season, allowing just three sacks on the season. He also hasn't missed a start in six seasons (103 straight starts overall) with the Texans and Chiefs. If he joined the Raiders, not only would he be able to play for a rival of the Chiefs fan base whose actions he referred to as "sickening and disgusting", but he would also be placed alongside his former Houston linemate, Mike Brisiel.
OG Kevin Boothe, 29, Giants
Boothe started 14 games his rookie season with the Raiders after they chose him in the sixth round of the 2006 draft out of Cornell. He then caught on with the Giants and has been on their two Super Bowl Championship teams during his six seasons with the team, including being the starting guard for the 2011 Super Bowl. The former Ivy Leaguer has shown incredible discipline as evidenced by his not having committed a penalty since the 2010 season. The Giants are reportedly making a hard push to keep him.
Despite outplaying starter, Brandon Fusco, in Minnesota, Geoff Schwartz has been relegated to backup. He allowed just four pressures on 84 pass blocks and also posted high marks as a run blocker. The Panthers originally drafted him in 2008 and he was a full time starter by 2010 where he graded out very well at both guard and tackle. He is a California native, having grown up in Los Angeles, so playing closer to home could be enticing for him.
OG Matt Slauson, 27, Jets
He reportedly visited the Raiders. He is another good under the radar guard on the market. He took a pay cut prior to last season to stay with the Jets and was making just over $1 million which means he shouldn't be expensive to sign. He is considered a very good pass blocker and a below average run blocker.
MLB Brad Jones, 26, Packers
This former outside linebacker flourished at middle linebacker last season for the Packers. His experience in coverage from the outside helped him put up some of the best coverage numbers among inside/middle linebackers. He also plays the run extremely well.
ILB Larry Grant, 28, 49ers
Grant was coached by Jason Tarver when he was a linebackers coach with the 49ers three seasons ago. He has sat behind the All Pro duo of Patrick Willis and NaVorro Bowman his entire career. It is time for a change of scenery or at least a slight change to across the bay. He is a native of Santa Rosa which is a few miles from Raiders training camp in Napa. Grant could prove as solid a replacement as any at the middle linebacker spot. That is if he feels up to the jump in responsibility.
OLB Kevin Burnett, 30, Dolphins
Burnett was cut when the Dolphins paid big money to steal Philip Wheeler from the Raiders. The moment Burnett came available, he instantly became the top rated free agent linebacker according to Pro Football Focus. If the Raiders were to sign Burnett and he played well, it would not be the first time this happened with Miami. The Dolphins signed Jack Grove as a free agent and dumped Samson Satele. The Raiders signed Satele and he has continued to have a solid career while Grove flopped out of the league. Kevin's brother, Kaelin, currently plays for the Raiders.
MLB Rey Maualuga, 26, Bengals
He has been effectively replaced in Cincinnati by Vontaze Burfict. While Maualuga struggles in pass coverage, he also had a career high in tackles (122). He also seems to have put his off the field problems behind him. Getting out of Cincinnati can only help continue his positive life path.
MLB Nick Barnett, 31, Bills
Reggie McKenzie and the Packers won the Super Bowl in Barnett's final season with the team. His numbers last season in Buffalo put him among the best linebackers in the league both in run support and coverage. He is also a very solid tackler which has been a real concern with the Raiders of late. He is a native of Fontana California (east of Los Angeles) so he could welcome finishing his career closer to home.
OLB Nick Roach, 27, Bears Signed with Raiders
Reported as visiting the Raiders today. No deal has been announced. Roach has been a full time starter the past four seasons on a solid Bears defense. He is a strongside linebacker which is what Kaluka Maiava is expected to play so the Raiders have filled the position.
ILB Karlos Dansby, 31, Dolphins
He has been one of the best inside linebackers in the NFL during his 9-year career with the Cardinals and Dolphins. He will be looking for his final contract and a chance to start.
MLB Dan Connor, 27, Cowboys
Visiting the Raiders today. He doesn't rate very highly as a linebacker but he is considered a pure middle linebacker. He had lost his starting job in Dallas and the Cowboys wanted him to take a pay cut. He refused so they cut him to save money. He had been considered a solid addition as a free agent two seasons ago from Carolina and has the potential to return to his previous form with a change of scenery.
CB Tracy Porter, 26, Broncos
The Raiders were interested in Porter last offseason. His defensive backs coach in New Orleans when he had the game-winning interception in the Super Bowl was Raiders head coach Dennis Allen so the interest is understandable. He had an overall disappointing season in Denver last season and will likely be in line for another one year deal.
FS Kerry Rhodes, 30, Cardinals
A Free Safety by trade, been injury free, full time starter for all but one season of his career. Still productive - had four interceptions last year along with 11 passes defended and 65 tackles. What more do you want?
I will try and keep this list updated as players are signed.