FWP just had a horrible season, is recovering from a broken bone, and has a FIRST ROUND PICK to compete with, who BTW is LOADS more talented than Parker.
Benson was given the starting job, did his best to lose it, and all they did was grab a questionable second round pick who is not nearly as talented as Benson. Sure Benson has sucked in the NFL, but he still has more talent than Forte.
It's not about FWP vs. Benson, it's about FWP vs. Mendenhall compared to Benson vs. Forte.
Parker rushed for 1,316 yards in 15 games last season, not exactly horrible

In 2006 Parker had roughly the same yardage and more TDs than Benson in his whole career.
And what makes you think that Forte is a questionable second round pick?
Benson simply was a wasted 1st round pick, he has a bad work ethic and isn't a very popular guy in the locker room, while Forte, on the other hand, is described as a high-character guy. The scouting report on nfl.com compares him to Edggerin James, so there must be some talent. While the jury is still out on Forte, we already know that Benson sucks...