They aren’t really fatties by cop standards and perps regularly outrun cops.
They mainly look to be small Latinas and they don’t have the male upper body strength of male cops for the four of them to hold onto the perp. Probably should have got him onto the ground and Sat on him, but were afraid he would have resisted sooner in that case.
I’ve heard that the police wear 30 pounds of equipment, which slows them down in a foot chase.