Executive Summary: Jenkins is worth much more than I think people expect. His expected production should be at least a second round pick in 2013, possibly a first (though it's unlikely for someone to part with a first). Based on a review of the draft, people expect entirely too much out of mid-round corners. I estimate there's less than a 10% chance of finding a corner equivalent to Jenkins in the third and fourth rounds of the NFL draft. And I estimate there's a less than 5% chance of finding a better corner.
Reports have been that the trade offers have been "compelling". I've seen "a [fourth] [third] at best" said so many times I can't count, and the range is as low as a seventh round pick. So let's consider what that means.
First, we have to discount the value of the pick. If someone is giving up a future draft pick, the rule of thumb is to discount the pick by a full round. Thus, if a team offers its 2013 first round pick, we value it as a second. A third round pick is valued as a fourth, and so on.
Next, let's look at the production that Jenkins would provide to another team. When he is healthy, everyone would expect Jenkins to start every single game for the Lions or the Colts. But what level of play should they expect? In 2009, we can all agree that Jenkins had a legitimate pro bowl season. The 2010 season is hard to gauge. There's no doubt that Jenkins played terribly. The doubt comes when trying to determine the cause -- did he simply quit with the rest of the defense? Or was that more indicative of his ability? Looking at the 2011 season, one would have to conclude the former. He wasn't great in 2011, but he was certainly closer to his 2009 performance than his 2010 performance. I think somewhere between that 2011 and 2009 performance is what you can reasonably expect out of Jenkins. That would put him among the better corners in the league, capable of starting every game and excelling at times. There's no doubt that he would be an immediate significant improvement for either the Colts or the Lions.
Now, let's compare what you can expect out of a drafted corner. Let's assume a team was willing to give us a 2013 second or third round draft pick -- generally higher than most people on this forum think he's worth. Those picks would discount to a 2012 third or fourth round pick (yes, the draft is over, but we have to discount). I ran numbers on every corner (as listed on NFL.com, though some have switched to safety and back) from 2008 forward to see what sort of player we're talking about. This amounted to a group of 54 players drafted, thus we should have a good feel for what you can expect out of these draft picks.
On average, these 54 players started only 3.0 games per season. And they played in 10.5 games per season (much of the snaps in those games probably were in special teams). By comparison, Jenkins started in 11.5 games per season and played in 14.5 games per season. Only 5 out of the 54 players started in at least 10 games per season. Only 13 of the 54 players started in at least 5 games per season. Over half of these draft picks have started in less than 2 games per season over their career.
These 54 players average 0.588 INTs per season. Jenkins averages 2.0 INTs per season (over three times as many INTs). Only 4 out of 54 players averaged more INTs per season than Jenkins. Nearly half of these players haven't even managed a single INT in their career. In all, I'd say there are only 3-4 players out of the 54 drafted in those rounds that I'd consider even in the same ball park as Mike Jenkins. None of them are appreciably better.
Based on this limited research, I'd estimate there's less than a 10% chance of finding a corner equivalent to Jenkins in the third and fourth rounds of the NFL draft. And I'd say there's a less than 5% chance of finding a better corner.
So, let me ask you. If you're the Colts or the Lions, and you're looking for a corner, what you would expect to receive more production from -- a third or fourth round pick? Or Mike Jenkins?