I had the same with my saluki x pup. She always plays too rough with my staffy, runs along side then grabs her on the back of the neck, trying to take her down with no fear at all. Was more worried that she was going to get knacked lol. She's been socialised just not off the leash!
I asked a mate for advice and he said let them get on with it, she needs to learn! sure enough after a few bundles and yelps she now enjoys the chase and runs circles round the staff but knows to keep just out of range or she'll get put in her place.