The same reason our Oline sucked until 'injuries', same reason dwill was getting more touches than Stewy, same reason we could finally shut receivers down after Norman got out of the 'doghouse' (and his injury)....
Rivera is a god awful evaluator and I'm not sure what the issue has been. Hopefully there's been a learning curve for him.
In Rivera's defense, there were actually injuries that kept those guys on the field.
Bene was quickly moving up the depth chart before getting injured. As soon as he was healthy he took over for Cason.
Boston was injured for TC and most of the season. He won his starting job pretty fast after getting healthy.
Delo was playing a lot because Stew was banged up. As soon as Stew was healthy they began splitting carries and eventually Stew took over. Yeah Delo went down but they were in no rush to get him back in.
Turner was hurt which kept him out.
Norwell was an udfa so you can't expect him to start from day one.
Remmers was signed late and started rather quickly after being signed.
So it's not like we had these eventual starters sitting on the bench for no reason.