Beane drafted a running back, traded for a running back, and made calls about two other high profile running backs (McCaffrey and Kamara). Does that sound like a GM that blames the offensive line and thinks the running backs are completely fine? I don’t think so.
He is clearly looking to improve the RB position, and I think you’ll see further proof of that when Singletary is not retained after the season.
When I go back and watch the All-22, I’m often yelling “ahh, there was a huge cutback lane there!”
Its less about what Singletary does do, and more about what he misses. You’re right that the offensive line is not good at run blocking, but there are still opportunities every game for cutbacks that he just doesn’t take.
I don’t know if he lacks the vision for it, or if he just understands his limitations and knows his lateral agility and speed would not be able to make the move necessary. Either way, it’s a problem for the Bills offense.
Take the following video of McCaffrey for example. You and I both know that Singletary would have plowed right into the hole in front of him for a 4 yard gain (the one McCaffrey originally takes), instead of taking the cutback that netted 20 yards. That will not change with a better offensive line. Singletary is who he is.