I think after so many years, it evens out. Barkley and henry didn't have great lines all the time. the defenses blitzed them often.
I think Zeke holding out hurt him. he came back and wasn't in football game shape...he was in shape, but being in football game shape is different. then he further slowed down in his third year and it just seemed to accelerate. yes, zeke carried a lot in his first year....and 3rd year and henry less to start, but then henry started to carry the load and he hasn't stopped and he has kept up his average. zeke YPC just kept dropping. Barkley was just unlucky and injury prone.....he has had a rivaval with Eagles and doing great with a great OL.
perhaps I am a bit biased because I didn't want us to pick a RB 4th in the draft. its a waste in this day and age of NFL.