Fantasy Upside
Brady was a top 3 QB from 2011-2012, and a top 7 QB in the two years prior to that. The Patriots' young WRs have another year of development from last year, and Belichick has done a fantastic job bringing in talent and competition at the WR position this offseason. We can reasonably expect Brady's receiving corps to be better than last year. If Gronkowski plays most of the season, Brady could easily see a return to the form that gave him three top five finishes in as many years, from 2010-2012.
Fantasy Downside
Several of Brady's weapons have struggled with injuries leading to missed time. We're not here to debate "injury-proneness," but all of Gronkowski, Vereen, Dobson and Amendola have all missed a fair amount of time over the last few years. If you take away a QB's best red zone target, his passing down specialist RB, and one of his best 3rd down targets and so forth... he's going to struggle. Brady may have top five (or top three) upside, but it's not unreasonable to think that Brady struggles this year, as he did last, and posts solid QB2 numbers. While nothing is wrong with solid QB2 numbers, you may want more production from a guy you're selecting to be your team's QB1.
Bottom Line
I think Brady's value all depends on where you are able to get him in your drafts. 4for4 ADP lists Brady at 7.12 in 12 team leagues, and 9.04 in 10 team leagues. If you can get him after his ADP, as the 9th or 10th QB off the board, you've drafted him more or less around his floor - and the upside is there. Since the news of Gronk not being on the PUP came in, Brady jumped to QB #7 in our ranks. So getting him as 7th QB off the board may be about right, but relative to the other QBs available later in drafts, Brady does present a little risk/reward. That said, his "worst case" is likely as a high end QB #2, and that's a really nice safety net to have in a player with Brady's upside.