I considered doing this, but I'm not sure it'd paint an accurate picture because we can only see current rosters, which don't include key players who are no longer on their teams (i.e. due to I/R). For instance here is Chris Lam's #1 scoring team, which averaged an amazing 190 PPG!
QB Manning, Eli QB NYG 20.4
RB McFadden, Darren B OAK 13.4
RB Moreno, Knowshon RB DEN 12.5
WR Green, A.J. WR CIN 20.8
WR Decker, Eric WR DEN 14.6
WR LaFell, Brandon B CAR 10.8
TE Gonzalez, Tony TE ATL 16
F Witten, Jason WR/RB/TE DAL 14.6
DST DST, Denver DST DEN 11.1
K Bironas, Rob K TEN 8.4
Vick, Michael B PHI 21.8
Bradford, Sam B STL 18.9
Foles, Nick B PHI 11.9
DST, New York (N) B NYG 10.3
Young, Titus B DET 9.6
Jones, Donald WR BUF 9.3
Brown, Bryce RB PHI 6.8
Smith, Kevin B DET 5.6
Peerman, Cedric B CIN 4.7
Hillman, Ronnie B DEN 4.2
Obviously, he got a great late surge from Bryce Brown. But even with his couple great games, does it look like a team that averaged 190 PPG? It seems to me that he must have lost some key players to injury after they'd contributed, seeing even using the best average PPGs from his current roster totals only 142.6 points. I'd guess he had McCoy and McGahee on this team too?
That said, at a quick glance of the playoff teams, Peyton Manning sure seems to be on a lot of them, so those who took the risk on him have surely seen ample reward. Ditto for Peterson.