[Mick]

Well, I disagree.
In my mind Bill Walsh could have, and would have, won Super Bowls with any number of reasonably competent QB's. Walsh consistently produced a true team effort which was not especially dependent on any one player or position. If one had to single out a position crucial to the success of a Bill Walsh team I would consider the entire offensive line to be that "position" (even though it's a unit of 5 guys rather than a single position).
As a pro Jim Plunkett was ineffective on the Patriots and his year or two with the 49ers. He had some great QB skills but they were only well utilized when he joined the good overall team, including OL, that Tom Flores had going for the Raiders.
For the first half of his pro career John Elway's performance did not produce many wins. Once Dan Reeves was fired Shannahan came in and got the Broncos playing well as a team.
Christian McCaffrey , as well as most all the other projected 1st and 2nd round draft picks, are all highly skilled world class athletes. Whether they have professional on field success, I think, is largely dependent on the competence of management, and coaching, of the team that drafts them.

I think Walsh could have won with mediocre quarterbacks, but chiefly because his defenses were so ridiculously strong over a very long period of time.  IMHO, George Seifert doesn't get nearly the amount of credit he deserves (multiple super bowl winning coach though he may be).  Here's the 49ers NFL Defense ranking from their 1981 Super Bowl Year through 2000, in points and yards:

1981  2, 2
1982  23, 21
1983  4, 10
1984  1, 10
1985  2, 14
1986  3, 6
1987  3, 1
1988  8, 3
1989  3, 4
1990  2, 3
1991  4, 6
1992  3,15
1993  16, 15
1994  6, 8
1995  2, 1
1996  4, 7
1997  3, 1
1998  13, 23
1999  30, 28

1996 was Seifert's last year, you can see what happened as it transitioned to Marriucci.  The horrible defensive rankings continued through Nolan, got a little better with Singletary (high water year with sSingletary was #4 points allowed in 2009, then immediately improved under Harbaugh and his four years:

2011  2, 4
2012  2, 3
2013  3, 5
2014  10, 5

Then Harbaugh left, and the team plummeted in defense to 18/29 and 32/32 in Chip Kellys Year of Misery.

Be interesting to see what happens this year.

[Mick]

Well, I disagree.
In my mind Bill Walsh could have, and would have, won Super Bowls with any number of reasonably competent QB's. Walsh consistently produced a true team effort which was not especially dependent on any one player or position. If one had to single out a position crucial to the success of a Bill Walsh team I would consider the entire offensive line to be that "position" (even though it's a unit of 5 guys rather than a single position).
As a pro Jim Plunkett was ineffective on the Patriots and his year or two with the 49ers. He had some great QB skills but they were only well utilized when he joined the good overall team, including OL, that Tom Flores had going for the Raiders.
For the first half of his pro career John Elway's performance did not produce many wins. Once Dan Reeves was fired Shannahan came in and got the Broncos playing well as a team.
Christian McCaffrey , as well as most all the other projected 1st and 2nd round draft picks, are all highly skilled world class athletes. Whether they have professional on field success, I think, is largely dependent on the competence of management, and coaching, of the team that drafts them.

I think Walsh could have won with mediocre quarterbacks, but chiefly because his defenses were so ridiculously strong over a very long period of time.  IMHO, George Seifert doesn't get nearly the amount of credit he deserves (multiple super bowl winning coach though he may be).  Here's the 49ers NFL Defense ranking from their 1981 Super Bowl Year through 2000, in points and yards:

1981  2, 2
1982  23, 21
1983  4, 10
1984  1, 10
1985  2, 14
1986  3, 6
1987  3, 1
1988  8, 3
1989  3, 4
1990  2, 3
1991  4, 6
1992  3,15
1993  16, 15
1994  6, 8
1995  2, 1
1996  4, 7
1997  3, 1
1998  13, 23
1999  30, 28

1996 was Seifert's last year, you can see what happened as it transitioned to Marriucci.  The horrible defensive rankings continued through Nolan, got a little better with Singletary (high water year with sSingletary was #4 points allowed in 2009, then immediately improved under Harbaugh and his four years:

2011  2, 4
2012  2, 3
2013  3, 5
2014  10, 5

Then Harbaugh left, and the team plummeted in defense to 18/29 and 32/32 in Chip Kellys Year of Misery.

Be interesting to see what happens this year.