Considering the fact that Herschel is a Tae-kwon-do black belt and Bo is pudgy, to be kind, these days, there wouldn't be a contest.
But these stats always make my eyes pop. And, remember, Herschel was supposedly a disappointment as a pro. From Wikipedia:
If Walker's USFL and NFL numbers are combined, he ranks as one of the most productive professional football runners in history. Many are reluctant to do this, however, because of the disagreement as to whether the level of play of the USFL was comparable to that of the NFL.UPDATE: Jim Brown, Lenny Moore, Marcus Allen, Marshall Faulke, Thurman Thomas... tell me that ain't bad ass company.
Even without taking his USFL numbers into account, his NFL stats are outstanding. In 12 NFL seasons, Walker gained 8,225 rushing yards, 4,859 receiving yards, and 5,084 kickoff-return yards. This gave him an impressive 18,168 total combined net yards, ranking him high among the NFL's top 20 all-time leaders in that category at the time of his retirement. As of 2007, 10 years after his retirement, he still ranks 8th in all-purpose yardage. He also scored 82 touchdowns (61 rushing and 21 receiving). Walker is the only player to have 10,000+ combined rushing and receiving yards and 5,000+ combined return yards(all of which were on kickoff returns). And also the only player to gain 4,000 yards three different ways: rushing, receiving, and kick off returns. He is one of six players (Jim Brown, Lenny Moore, Marcus Allen, Marshall Faulk, and Thurman Thomas) to exceed 60 TDs rushing and 20 TDs receiving.