Size - Running backs come in a number of different sizes, especially when you include fullbacks, but there are some things to be wary of. The most obvious, although there are rare exceptions, are guys that are too small to hold up to the pounding they'll take in the NFL. If you've got a guy on a six-foot frame who weighs just 175 pounds, chances are he's going to get broken in half by your average NFL lineman. I like running backs around the 5'10"-6'2" range, which is a frame that will allow them to carry the bulk they need in the NFL. Backs taller than this tend to be easier to get under by the defender. In other words, the defender can get in under the shoulder pads to stand the runner up and drive him backwards. I like the guy that's a bit shorter, with a lower center of gravity. He tends to have better balance and sometimes defenders lose him behind his offensive linemen. I also like to see his weight somewhere between 210 and 230 for a halfback and 240-250 for a fullback, although I certainly would not rule out a player because he doesn't measure up to these traits. There are always exceptions.