I will respectfully disagree with your assessment. Nelson's and Adams' drop rates may be comparable at this point in their career but there are more to Adams' drops than just that. I think you have to look at what kind of passes were dropped as well as how many targeted passes were caught, which shows how often they were able to make a play on the ball.
Look at at Adams' reception rate. When targeted this year, Adams caught 53% of Rodgers' passes. Nelson in 2009 caught 70% of his targets. Has Rodgers been off this year? Yes, and that has undoubtedly affected Adams' numbers but still, that is an enormous difference and Adams is definitely at fault. He hasn't been able to make a play on the ball when it's been in his vicinity. Also, look at Adams' y/r this year. It's 9.7. That's not exactly good, in fact it's number 113 out of 154 receivers this season. Nelson's in 2009 was 14.5. Once again, there are other contributing factors that may explain the wide gap but certainly some of the blame goes on Adams. Those numbers also make me believe (as does my memory) that many of Nelson's drops were deep passes, which are indisputably tougher to catch. Adams' very low y/r I think shows he has struggled to catch even very basic short passes. I just don't agree that comparing Nelson and Adams (in terms of drops at least) is as easy as saying "well, they had a comparable drop percentage." This isn't even to mention that Adams hasn't even remotely looked on the same page as Rodgers much of this season.
Also to factor in is that Jordy made up for a lot of his drops with spectacular catches. Not until this season did I really appreciate what an athlete he is, and how many insane catches he is capable of making. Adams just doesn't have (or at least hasn't shown to me) that same athletic ability. Jones has had it at times, but I'm just not impressed with Adams at all, though I will acknowledge he played a little bit better on Sunday.