Why not compare Maroney to other second-year running backs over a period of time, say fifteen years? We can see how he stacks up against his own peers, and should be able to see where he falls in the crowd of true sensations (such as Tomlinson and Peterson) and the JAG crowd that so many have touted him as being.
I have used Yds/g as the standard, since I feel it is better than total yards, and have added in the total number of attempts, to see roughly how often he is used, and how often he plays, in comparison.
Here is this season (Att, Yds/G):
2007
Addai 202 87.6
White 199 63.1
Maroney 105 58.4
Jones-Drew 134 52.6
Bush 144 47.0
2006 (full season stats, naturally)
Frank Gore 312 105.9
Ron Brown 241 77.5
Cad Williams 225 57.0
Cedric Houston 113 46.8
Cedric Benson 157 43.1
Marion barber 135 40.9
Etc., with +40 carries: Morency, Brandon Jacobs, Gado, Jason Wright
2005
Willie Parker 255 80.1
Julius Jones 257 76.4
Steven Jackson 254 69.7
Tatum Bell 173 61.4
Kevin Jones 186 51.1
Etc., with +40 carries: Mewelde Moore, Greg Jones, Bruce Perry, Maurice Hicks, Michael Turner, Chris Perry, Shaud Williams
2004
Chris Brown 220 97.0
Dom Williams 302 79.2
Lee Suggs 199 74.4
Willis McGahee 284 70.5
Larry Johnson 120 58.1
Quentin Griffin 85 51.8
Onterrio Smith 124 49.5
Etc., with +40 carries: Hicks, Henry, Pinner, Toefield
2003
Clinton Portis 290 122.4
William green 142 79.9
T.J. Duckett 197 48.7
Brian Westbrook 117 40.9
DeShaun Foster 113 30.6
Lamar Gordon 71 39.8
Etc., with +40 carries: Betts, Davenport, Cartwright, Chester Taylor, Tony Fisher
2002
Tomlinson 372 105.2
McAllister 325 92.5
Travis Henry 325 89.9
Michael Bennett 255 81
Anthony Thomas 214 60.1
Marcel Shipp 188 55.6
Etc., with +40 carries: Kevan Barlow, Dee Brown, Lamont Jordon, Nick Goings, Travis Minor
2001
Shaun Alexander 309 82.4
Maurice Smith 237 47.5
Ron Dayne 180 43.1
Mike Anderson 175 42.4
Troy Hambrick 113 36.2
Etc., with +40 carries: Jamel White, Trung Canidate, Thomas Jones, Shawn Bryson, Doug Chapman
*****
That's enough for now, except that I will point out some other players who had very disappointing sophomore years:
Sammy Morris (2001) 20 carries for 4.5 Yards/game
Rudi Johnson (2002) 17 for 9.6/game
Justin Fargas (2004) 35 for 10.5/game
Amos Zeroue (2000) 6 for 1.2/game
Ahman Green (1999) 26 for 8.6/game
Tiki Barber (1998) 52 for 10.4/game
Tyrone Wheatley (1996) 112 for 28.6/game
Stephen Davis (1997) 141 for 40.5/game
Garrison Hearst (1994) 37 for 21.1/game
Robert Smith (1994) 31 for 7.6/game
And arguably comparable to Maroney:
Priest Holmes (1998) 233 for 63/game
Duce Staley (1998) 258 for 66.6/game
Napoleon Kaufman (1996) 150 for 54.6/game (the closest in terms of usage)
Jerome Bettis (1994) 319 for 64.1/game (more productive thus far, but also HOF-bound)
******
Let's consider these numbers together.