Posted this in another thread a few days ago:
	
		
	
	
		
		
			Don't want to drag this discussion too far off topic, but did want to offer one last little nugget about Mendenhall. Here is a list of all active NFL RBs who have at least three seasons of 200+ carries:
Steven Jackson
Willis McGahee
Frank Gore
Adrian Peterson
Michael Turner
Cedric Benson
Maurice Jones-Drew
Chris Johnson
Marshawn Lynch
Matt Forte
Ray Rice
Ronnie Brown
Brandon Jacobs
Arian Foster
Rashard Mendenhall
LeSean McCoy
Pretty exclusive company. There are 1-2 names on this list that don't do much for me, but by and large it reads like a "who's who" of elite RBs from the past decade. It shows the kind of talent you need if you're going to last as a long term starter in the NFL. Competition for places is extreme. You'll see some guys win starting jobs by default if they were high draft picks and/or if they happened to be in the right place at the right time, but if you are a weak link then you will be found out sooner rather than later, and will generally be replaced within 1-2 years.
The fact that Mendenhall was able to last 3 years as a starter on a playoff team and only lost his job after a serious knee injury pokes some holes in the idea that he's just this mediocre, backup caliber talent. To look at his success as a product of opportunity is to miss a big part of the equation, which is that (in the long run) talent is the reason why players receive opportunities. If he wasn't very good, he would've been replaced long before now. Pittsburgh didn't draft a back in the top 5 rounds at any point during his tenure. They didn't sign any real free agent competition. All of those things indicate a team that felt fine about its RB situation.
Blount's career trajectory more closesly resembles someone like Slaton or Hillis. One good year out nowhere. Reduced effectiveness and workload the following year. Replaced soon thereafter. Irrelevant from that point forward.
		
		
	 
If we're trying to figure out Mendenhall's future then I thought it would be useful to consider how similar players have fared. Of all the RBs in the NFL right now who have at least three seasons of 200+ carries, here is how they rank in terms of total number of seasons with at least 200+ carries.
Steven Jackson - 8
Frank Gore - 7
Adrian Peterson - 6
Willis McGahee - 5
Chris Johnson - 5
Marshawn Lynch - 5
Matt Forte - 5
Michael Turner - 4
Cedric Benson - 4
Ray Rice - 4
Ronnie Brown - 4
Maurice Jones-Drew - 3
Brandon Jacobs - 3
Arian Foster - 3
Rashard Mendenhall - 3
LeSean McCoy - 3
A few things stand out to me:
- 11 of 16 (69%) players who managed 3 seasons of 200+ carries had at least one additional season of 200+ carries.
- The average number of 200+ carries seasons from this group is 4.5.
These numbers suggest that any back who manages to accumulate three 200+ carry seasons is far more likely than not to have at least one more 200+ season. However, there's an obvious problem with using this group of players. They aren't retired yet, and thus their careers are incomplete. It's highly likely that some players like McCoy, Foster, Rice, and Lynch have additional 200+ seasons left on their tires. Thus the estimates that you get from this group are likely to be extremely conservative.
For that purpose I thought it might be useful to look at other recent backs whose careers are completely over. Here is a list of all NFL RBs who retired within the past decade who logged at least 200 carries in at least three seasons. The list is sorted by the number of 200+ carry seasons, from most to least.
Emmitt Smith - 14
Curtis Martin - 11
Jerome Bettis - 10
LaDainian Tomlinson - 10
Marshall Faulk - 9
Edgerrin James - 8
Eddie George - 8
Warrick Dunn - 8
Corey Dillon - 8
Jamal Lewis - 8
Fred Taylor - 7
Thomas Jones - 7
Shaun Alexander - 7
Ricky Williams - 6
Clinton Portis - 6
Tiki Barber - 6
Ahman Green - 6
Garrison Hearst - 6
Stephen Davis - 5
Priest Holmes - 4
Willie Parker - 4
Rudi Johnson - 4
Travis Henry - 4
Deuce McAllister - 4
Charlie Garner - 3
Duce Staley - 3
Antowain Smith - 3
Michael Pittman - 3
Brian Westbrook - 3
Adrian Murrell - 3
Marion Barber III - 3
Joseph Addai - 3
Cadillac Williams - 3
Anthony Thomas - 3
Reuben Droughns - 3
If you do the calculations for this group...
- 24 of 35 (68.5%) of RBs who had at least three seasons of 200+ carries had at least one additional 200+ carry season.
- The average number of career 200+ carry seasons for this group is 5.8.
What this tells me is that if you take all subjectivity out of the equation, Mendenhall has a 68.5% chance of having at least one additional 200+ carry season and an expected yield of 2.8 additional 200+ carry seasons.
Of course, there are different ways to frame the stats and what you choose to emphasize will undoubtedly change the results. For example, the 200+ carry season metric that I've chosen is a bit arbitrary. If you looked at players in terms of average carries per season or carries by age, you would probably get different results. The really exceptional talents like Tomlinson, Martin, and Emmitt had a totally unbroken chain of 200+ carry seasons beginning with their first year and continuing for a very long time after that. The fact that Mendenhall only has one 250+ carry season after five years in the league would put him in different company from the likes of them. Likewise, if you used 300+ carry seasons, the results would also look a lot different.
Nevertheless, no matter which metric you use, they're likely to point towards the same conclusion: 
any RB who is talented enough to command a large workload over his first several seasons is likely to continue doing so. If you want to look for negative comparisons for Mendenhall, you can point towards guys like Anthony Thomas, Joseph Addai, and Duce Staley who produced early for the team that drafted them before fading into irrelevancy later in their careers. On the other hand, there are guys like Tiki Barber, Thomas Jones, and Charlie Garner who were much less productive than Mendenhall up to this stage of their careers, but made up for it with a string of good seasons on the back end. Based on history, I think he probably has at least 1-2 useful seasons left. We will have to wait and see though...