The thing with Penny is, he's incredibly talented, so tantalizing that you're going to keep giving him chance after chance. Because if ever can put it together for a whole season, he could be a 2000 yard 25 TD back.
And even if he never has a complete season, 10 games of Penny is still better than not having him on the roster.
I am a little concerned when looking at his numbers last year. He feasted on soft boxes. (Teams taking away Wilson's deep ball.) He only averaged around 3.5 ypc against stacked boxes. But generally didn't run him against stacked boxes so small sample size.
Penny shouldn't get a single carry in the Preseason. Walker should also get very few, imo, but will probably get a lot. I'd like to see Dallas be the bellcow of the pre-season.