For those interested, let's take a look to see if the often perpetuated idea that these two are relative equals is actually true (as of 9/19).
HITTING THE BASEBALL:
They are comparable hitters in terms of actual OPS. Ike hits for more power and walks more, Lucas Duda hit for a slightly higher average. There's one problem with this. Ike Davis 2012 BABIP. Lucas' numbers seem pretty steady over his MLB time, while Ike has seen a drastic drop in his BABIP in 2012. If we expect that number (.245) to climb much closer to his ~.300 average, we should expect the difference in average between the two players to tip in Ike's favor.
So, we can conclude that Ike is the superior hitter in every category, but all told he's still only a marginally better hitter than Duda. Both guys should be perennial .800+ OPS guys moving into their prime.
RUNNING THE BASES
Ike has been worth 0.5 runs on the basepath in his career.
Neither is very good, but once again, Ike has been better.
CATCHING BASEBALLS (defense)
I think we all know the answer here. Ike is the far superior defender. In fact, it's not even close.
Ike has a career UZR of 8.1. Duda? -34.1. Yup. You read that correctly. Now it's true that a shift to 1b would likely mitigate some of Duda's defensive awfulness, but Ike is still far superior at that position.
In summary, Ike is better at every aspect of the game. It's really that simple. In a similar number of plate appearances, and despite nearly missing an entire season, contracting a possibly career debilitating disease, and suffering from extreme BABIP bad luck, Ike has been worth 5.9 wins for this team. Duda, without suffering from any BABIP issues, any serious layoffs from injury etc. has been worth all of -0.1 wins.
So, is Ike off the table for any potential trades? No. Of course not. If the right one comes along, we should take it. But we should also stop saying they're essentially the same player, because they're not. Similar perhaps, but Duda is simply not as good at this point in his career.
Oh, and Duda is a year older.