Without knowing what it would take to acquire Carson Palmer in trade, I can not endorse Palmer. But we can at least look at Palmer the asset, ballpark what he's worth and determine if he's a sound investment independent of his cost.
Let's look at the basics first: Palmer is 31 and does not turn 32 until December 27. That means, for our purposes, 2011 is Palmer's age 31 season, 2012 is his age 32 season and so on. Now let's look at that handy aging curve provided by Pro Football Reference:
That covers his remaining contract. That's one peak season, two near-peak seasons and one season into the decline. That's pretty attractive on the whole. Three to four seasons isn't a Brady, Manning or Rivers sized window, but for those of us fighting over the scraps, that's filet mignon.
Helping Palmer to potentially outperform historical trends are his tools. Palmer is a former first overall pick and not a garden variety first overall pick, if such a thing is possible. We're in draft season and so hyperbole has replaced perspective, but consider this prospect:
Athletic, cannon arm
Four year starter, 45 starts, all in a pro-style offense (Paul Hackett, Hue Jackson, Norm Chow)
59.1% career completion percentage
7.5 yards an attempt
No prospect in this class can touch that. Andrew Luck, hyped as a once in a decade prospect, can not touch that. He's not as big, doesn't have the same kind of arm strength, is not nearly as experienced (and didn't start as a true freshman) and hasn't been as successful. Now, tools, performance, experience--that doesn't wholly define a prospect, and I am not saying Luck couldn't surpass Palmer, especially if he can turn in another season like his 2010, but if the above were affixed to, say, Jake Locker, teams would be stabbing each other in the ball trying to trade up for the first overall pick.