The least of Malcolm's problems is his speed. He has proven time and again he can run down players. His has more issue getting looked away from where he will need to be and he has really struggled being opportunistic with the ball in the air. He may be better suited as a SS as his coverage skills are better than Harper in man cover, he supports the run decently and does have a nose for dislodging the ball. He hasn't proven himself as adept a pass rusher as Harper but it could only be lack of opportunity.

Frankly, if we were somehow able to upgrade FS with a better ballhawk, I could see Jenkins at SS and Harper re-signed for cheaper as both depth as well as in big nickel schemes or even as a flat out speed mismatch double edge rush. Kind of a hybrid safety position in lieu of a OLB in passing downs.

Who other then Vincent Jackson has he run down?

Well for one example the Dallas game where he ran down Roy Williams and forced the game winning fumble on what would have been a sure TD.