I can think of some unkowns/X-factors that don't all have to do with players, and many things on my list may have been mentioned already (I haven't read the entire thread, but thought the O.P.'s idea was a solid one and went from there. It's 15 items long, so my apologies if I bore the reader
:
1.) Number of WRs kept:
This will impact offensive diversity in the play calling, which leads to......
2.) McDaniels' playcalling:
Does he continue the focus on the two tight ends and WWW, or does he get Brady to make some significant changes, either just by spreading out the ball more or by going more WR-centric?
3.) Vollmer's back:
Can the man stay healthy
4.) Waters' age:
Does the man hit the wall this season (assuming he plays)?
5.) Rookie development:
This team needs significant production from Hightower and at least one of the DBs this season.
6.) Health/Improvement in the defensive secondary:
Can Dowling and Chung stay healthy? Can Dowling play? Will McCourty suck again this season, or will he and the team get his play straightened out?
7.) Defensive "coordinator":
Does BB take less of a hands on approach, and how does that impact that defense?
8.) Mesko:
Can he keep improving on what was already a quality season in terms of return numbers and touchbacks?
9.) Gostkowski:
Another year away from his injury, will his leg strength and confidence fully return?
10.) Concussions: Can this team avoid the concussion problems that seemed to have an impact on the offense last season (i.e. Solder/Woodhead)?
11.) Schedule: Can the team take advantage of the easy schedule by holding up against the few 'trouble' spots on it? At B-more following a west coast trip, at Jets after another west coast trip, Texans & 49ers after back-to-back divisional road games against the Jets and Dolphins....
12.) Getting the band back together:
How much does getting Gaffney and McDaniels (and having a new WR who already knows a lot of the system, in Lloyd) give the Patriots an edge early in the year?
13.) Carter's injury:
Assuming he returns, how long does it take him to return to 100%?
14.) Potential change in defensive base formation:
A change from the 4-3 to the 3-4 seems to be a real possibility, especially given who was taken in round 1. The linebackers have a potential to be a legitimate strength against the run, and to at least hold their own overall, for the first time since 2007. Of course, the flip side is that a couple of DEs are going to really have to step up in order to help the D-line stay strong at the point of attack.
15.) RB involvment:
Both a personnel issue and a playcalling issue variant, the questions here are about who'll be toting the rock, how often that toting will happen, and whether or not the team will return to throwing the ball to the receivers.