Stats dont tell the whole story but here are Bijan Robinsons numbers last 2 years with and without Drew Dalman.

Bijan in 22 starts with Drew Dalman 4.9 yards per carry and 79.1 yards a game

Bijan in 11 starts without Drew Dalman 4.2 yards per carry and 62.8 yards per game

I kinda cheated and didnt include 1 game against the Chiefs this year which drew dalman left in the 2nd quarter and played 31% of snaps. But even if you include that game it points a positive for Dalman as Bijan was averaging 2.6 a a carry that game with Dalman in (not great i know) but after Dalman left Bijan was averaging just 1.6 the rest of the game