You have to factor in the age of both players as well. ARod is 31 (and will turn 32 during next year) while Zambrano is 25. As muntjack said, Zambrano still has a lot of room to improve where as ARod likely isn't going to improve much anymore. He may stay the same but he likely won't show a significant improvement. In your previous post you posed the question: Is ARod one of the top 5 positional players in the game? Well, there were 22 players that had a better OPS in 2006 than ARod did. There were 17 players that had more HR's than ARod did in 2006. Then factor in age. A .914 OPS for a player at 25 looks a whole lot better than a .914 OPS for a player at 31. Just off the top of my head, I'll take Pujols, Howard, Cabrera, Hafner, Wright over ARod any day of the week. I'm sure there are many others but those popped into my head.