because we either run...or pass. not much play action, nothing to TEs, and nothing quick. this allows easy reads for lbs to help in pass coverage. same reason the dump off to the rb is open a lot when they arent in pass pro. but then teams blitz, putting them in passpro and eliminating them as a receiver. this is where their size comes in as a negative because then they are not big enough to block LBs long enough for chaney's pass plays to develop. not much help when the OL doesnt do their job either.