I'm not sure why the Mets and Yankees are basically denying that a Sheffield/Cameron swap wouldn't be a good idea in some ways. The Yankees desperately need to improve their defense, and the Mets could use another bat. Let's check out their Net Runs to see how much one team might lose by making this swap. To figure Rate, I'll use Richard Wade's Established Level of Performance formula to get a better grip on their defensive talents. This formula is as stated:
(3 * AdjGx * Rate2x + 2 * AdjGy * Rate2y + AdjGz * Rate2z) / (3 * AdjGx + 2 * AdjGy + AdjGz)
X=most recent year, Y=second most recent, and Z=third most recent
For those who don't know, Rate is Runs Above League Average per 100 games played defensively. Rate2 is the adjusted for league difficulty version. 100 is league average, so when I say Rate2 Runs, I mean those above or below 100.
Sheffield's last three defensive seasons in right:
143.3 AdjG; 103 Rate2
132.3 AdjG; 101 Rate2
70.3 AdjG; 100 Rate2
Cameron's last three defensive seasons in center:
144.3 AdjG; 110 Rate2
132.4 AdjG; 104 Rate2
9.0 AdjG; 89 Rate2
Net Runs = MLVr*100 G + Rate2 Runs
.267* 100 G = 26.7 + 1 = 27.1 R/100 G
27.1/100 = .271 R/G
.318* 100 G = 31.8 + 5 = 36.8 R/100 G
36.8/100 = .368 R/G
I see that the difference is only roughly 10 runs, but I think Cameron's EPL is skewed by a small sample in centerfield this year. He is better than +5 runs in centerfield, so the difference would be greater, and the added value of getting Womack out of the outfield and the lineup far outweighs the 10 runs I've shown here.
Supposedly the Mets approached the Yankees with this trade. As you can see here, the team who rejected it is the team who needs it the most. Nevermind the fact that Cameron is outperforming Sheffield at the plate; let's pretend that he is hitting for less value but fielding for more. Check out the Yankees Defensive Efficiency in comparison to the Mets to see who needs Cameron in the outfield more:
NYA Def. Eff.: 0.674 (27th in MLB)
NYN Def. Eff.: 0.699 (14th in MLB)
Take the fact that Cameron is outperforming Sheffield offensively and defensively, and the fact that the Yankees need more defense like no other possibly contending team in the league, and it is amazing that the Yankees throw this trade proposal out the window. Getting Cameron to play centerfield for them would also allow NY to sit Tony Womack and let Bernie Williams play RF. I understand Williams is struggling, but if he is placed in right they may be much better off than if they had Womack in the lineup.
So maybe neither of them is a positive boost; would you rather the player who is worth -1/3 (-.341 Womack) of a run per game, or the one who takes 6 games (-.348) to pile up as much negative value. I understand neither is that sexy a proposition, but its the situation at hand.