I guess it just boils down to how you define a "big power back." When I hear that term I think of guys like Alstott, Jacobs, McClain; North/South runners that are 250#s or more. "Lumbering loads." And, I'm not even talkin' about bruiser types like Stephen Jackson, Marion Barber or Jonthan Stewart...not sure if Michael Turner is in this group too.
To me, Mendenhall is an "every down back" or "all purpose runner" that well, can do it all. Adrian Peterson, Frank Gore, LeSean McCoy or Ray Rice type of back. Obviously, some of these guys tend to be built more towards the power end while others are built more for speed.
A guy like Bettis...? Chances are we won't ever see that kind of player, with that kind of size, with that kind of career, ever again.
Yeah, it's a bit gray, but I think we're on the same page as far as terminology.
Listed weights, those above:
B. Jacobs - 264# (3,524 career rushing yards)
McClain - 260# (1,113 career rushing yards)
M. Alstott - 248# (Retired, 5,088 career rushing yards)
L. Blount - 247# (27 career rushing yards)
M. Turner - 244# (4,058 career rushing yards)
S. Jackson - 236# (6,921 career rushing yards)
J. Stewart - 235# (2,037 career rushing yards)
M. Barber - 218# (4,109 career rushing yards)
A. Peterson - 217# (4,876 career rushing yards)
F. Gore - 217# (5,754 career rushing yards)
R. Rice - 212# (2,003 career rushing yards)
L. McCoy - 208# (846 career rushing yards)
Agree that a big power back is ~ that 250# threshold. Consistent and prolific means you're scratching at 10K yards. Turner's the most likely to fit both criteria here, but I don't think he breaks 7K due to wear and tear. Jackson could hit 10K, but injuries are tolling him hard, and he's not really at that 250# region. Jacobs looks spent. I love McClain, but he's a long ways off and not the feature back.
Bettis is god.