Peterson has played 14, 16, 16, 15, and 12 games in the seasons since he's come into the league. Cant stay healthy? Not sure where you're getting that from (maybe college?). Fred Jackson has out shined 1 1st round pick so far, Marshawn Lynch. Its unfair to say that he's out shined Spiller because we dont have a large sample size on him, and the sample size we do have shows that he can be a very good back.
If you're asking why to Foster, than obviously you havent seen his stats. In the past 2 years: 2,840 yards rushing, 26 TDs, 4.7 ypc. 119 rec, 1,221 yds, 4 TDs. Good luck finding someone that has outproduced Foster in that same time frame.
Mccoy had over 1,600 total yds and 20 Tds last year alone.
Rice had over 2,000 total yds and 15 Tds last year alone.
Just for reference: Jackson has had over 1,300 total yds and 6 tds in 10 games. Also, you can say "give me a young Freddie over any of them" but the fact is that he is 31.
You have to look at track record and the previous year or 2 to determine who the best back in football is. Why don't you try to think of who you would trade Fred for at this point?
Peterson
Foster
MJD
Forte
Rice
McCoy
Gore
I would probably trade Freddie for everyone on that list except for Gore.