"Win Shares" attempts to value players based upon the amount of wins that they generated for their team above the average player. If you are interested in the methodology, go read the post called "HOF Positional Players Win Shares" that appeared on 1/19/11.
I took each of the candidates and have the following information.
Offense is relatively simple. You take that player's controllable stats (hits, 2b's, 3b's, BB's, HR's) and compare them against the average player in that same division (found on the team stats page).
For defense, it is a bit more subjective. Basically you value a player's worth in the field relative to an "average" player at that position using plus/minus plays, fielding percentage, and other defensive statistics. Since the "average player" is worth 0 wins over .500 for a team, and since the "average player" will not always be able to be an average SS or CF, positional adjustments must come into play. Stolen bases and stolen base attempts are also used.
In Season 25, the average AL player batted .269, hit doubles on 15.5% of their hits, triples on 1.5% of their hits, homers on 13.7% of their hits, and walks on 8.4% of their plate appearances.
In the NL, the average player batted .263, hit doubles on 15% of their hits, triples on 17% of their hits, homers on 12.7% of their hits, and walks on 8.1% of their plate appearances.
1. Henry Wise - 4.39
2. Marshall Devereaux - 3.13
3. Trenidad Trajano - 2.70
4. Davy Moreno - 2.60
5. Alex Limon - 1.06
1. Adam Gose - 4.66
2. Zachrey Betancourt - 4.45
3. Yorman Molina
4. Gregg Fuller - 3.69
5. Benny Rivera - 2.80