There actually are a few candidates who comes to mind. Here are the most likely candidates for the honor and why.
Through the first part of the season, he was without question the MVP of this offense. He was on a record pace and was the saving grace in an otherwise flawed and clunky offense. Through the first seven games, the Raiders had just come off two straight wins which followed a hard fought close loss to a very good Falcons team. This put them just one game away from .500 at 3-4. Palmer had 9 touchdowns to 5 interceptions and had thrown a touchdown pass in all but one game on the season. His passer rating went over 100 twice and never dipped below 73. It wasn't phenomenal but it was the saving grace of the squad. But it would get no better than that. In fact, it would get far worse.
The Raiders then reeled off six straight losses and Palmer put up a streak of nine straight games with an interception - most of which were of the game-killing variety. All the while most of Palmer's touchdown passes happened in garbage time. The Raider finally won a game but they did it without putting the ball in the endzone once. He played just over 14 games with the first half being pretty good and the last half being quite brutal.
Reece stepped up when Darren McFadden went out with an ankle sprain and he played quite well. He was given three starts in McFadden's absence and played better than McFadden had in most of his starts on the season. He is currently second on the team in several categories: rushing, catches, yards from scrimmage, and yards per carry among running backs. He also has more receiving yards than any other running back on the team. All this, and he is supposed to be a fullback. Most fullbacks just block and get none of the glory for the holes they open for the man behind them. He blocked as well which means he did a lot of work for this Raiders team.
I don't care what anyone says, no one outside of Brandon Myers' mom thought he was capable of the numbers he put up this season. He leads the team in catches (75) and receiving yards (753). No Raider tight end has put up those kind of numbers since Todd Christensen had 95 catches for 1247 yards in 1986. Zach Miller led the Raiders in receiving for three straight seasons from 2008-10. He topped out at 805 yards receiving which Myers needs 53 yards to surpass. He seemed well on his way to blowing that number out of the water but since he tied a Raider record with 14 catches in week 13 against the Browns, he has had just six catches for 32 yards.
In a season in which the Raiders receiving corps has been known for running the wrong routes and dropping the ball, Streater has been a bright spot. He doesn't have as many yards as Denarius Moore or Darrius Heyward-Bey but he has come on strong of late and has been the best wide receiver on this team the last four weeks. He has 507 yards receiving on the season but more than half of those yards came from weeks 13 thru 15. And in a what-have-you-done-for-me-lately game, that means a lot. Need I remind anyone, he was an undrafted free agent? Not that it should matter whether he was drafted but it kind of does. It means the Raiders were able to use their draft picks elsewhere and essentially got a freebie in Streater. That's value.
Per Pro Football Focus "Jared Veldheer should be considerd [for Raiders MVP]. Solid every down work." I can't argue with that. And I wouldn't argue with PFF when it comes to offensive line performance. The offensive line as a whole has not played well and Veldheer has made a few mistakes but overall he has played quite well. It goes relatively unsung with the poor run blocking and constant pressure Carson Palmer is under.