One man's take:
First of all, I must apologize for some egregious omissions. Tom Casey, Bob McNamara, and Charlie Shepard should all have been included on the list, and would in my mind rank above some of the others this list, but in the end 13 was a sizable number in itself, and I don't believe any of these omitted players would have cracked the top 2.
From this list-
13) Miller - Great rookie season, but the focus of those Bomber teams was Brock's passing, not Miller's running.
12) Richardson - only back to ever win a rushing title in a 16 game or more season with less than 1000 yards (beat out Damon Allen 925-920 in 1993). Like Miller, was serviceable but not the key element of a pass happy offense.
11) Reid - a very strong 2010 season, and a game for the ages against BC (260 yards, 3rd best ever) in the only successful display of the otherwise goofy "Jet Package" (does it bother anyone else that the greatest rushing AND passing games in Bomber history are both products of the Mike Kelly offensive system? Maybe "The Source" will chime in). But Reid, an admirable replacement for Charlie Roberts, never felt like a game changer at running back to me.
10) Mimbs - Holds the single season rushing record - the only Bomber ever to rush for a mile in one year. So why do I not really remember anything about him? A very underrated back, if he had hung around for a few more years would rank higher.
9) Washington - very steady numbers, he was good for 1000 or so every year, but was buried on some poor teams which lowers his profile
8) Raimey - Like Washington, very good numbers over an extended period, but stuck on some poor teams, and replacing a legend in Leo Lewis he suffers by comparison. One of the best backs on the list in terms of pass catching, and he was a star returner as well, which moves him up on the list.
7) Herron - Destined for greatness, especially after that revelatory 1972 season, but a drug bust in the off-season led to his departure, so he does not have the mileage to crack the top 6. Depending on my mood, he could slide as low as #10 on this list for me.
The top 6 are now in the "has done something no other Bomber RB ever did" category, so they get raised a level above:
5 tie) James and Harris - I said before Harris was in tough to crack the top 5, which I am sure will be met with some flak from younger MBB members. So I'll put him in a tie with KId Dymamite (maybe if Harris had a cool nickname he might rank higher). Both are Winnipeg natives and grads of our high school football programs. James' numbers appear smaller, but he had to share time with Lewis, Casey, McNamara, and Shepard, and was still able to put up some heady numbers (18 rushing TDs in one season!) and be the best Canadian on the team 4 times, one more than Harris. Harris has more all-star nods, and is arguably the best dual threat runner/receiver the club has ever employed at running back (although Leo Lewis makes a pretty compelling case as a receiver too). Trying not to let James' moonlighting as an NHLer at the same time influence me - I will hedge my bets and place both of them at the edge of the top 5. In the "only player ever to...." category, no one else has ever hit 1000+ rushing-800+ receiving yards in one season in CFL history (Harris) or played both the Stanley Cup and Grey Cup in the same season, or for that matter a Grey Cup and NHL game IN THE SAME DAY (James)
4) Hanson - no stats make a comparison hard, but he was the first player to ever put the Bombers on the map, and was THE team by all accounts in his playing days. His "only player ever to..." contribution? Name another Bomber who was the best male athlete in the nation across all sports. Can't? That's because no one else ever has been honoured as such. That puts him up to #4 for me.
3) Reaves - My 1984 bias clearly on display, but he is the only Bomber RB to ever be selected as the Most Outstanding Player in the CFL, so that rarified air of top 3 is warranted to me. He boasted before the year started that he wanted to hit 1800 rushing yards, and came oh so close to hitting it, despite being the primary target in every game. The Bomber game plan was "run on first down for 5-6 yards, short pass play on 2nd down, repeat down the field". A classic power back with deceptive speed and brilliant vision and cutting ability for a big man, has was essentially automatic for 20 carries and 100 yards a game. Even his lesser seasons were quite impressive ("only" 1323 yards in an off year in 1985 ,1471 in 1987). He was the focal point of the offence for 5 years here.
2) Lewis - Bud Grant called him "the greatest player I ever coached". I defy anyone to come up with a better counter-argument as to why Lewis should not be on the all-time team. Still the career leader in all-purpose yards for the club, and #2 in career rushing, in a committee running system he was still the most dominant player on the team during the club's 50-'s-60's heyday. Threat as a runner, receiver, and returner, he did it all. His "only player to..." list includes winning 4 Grey Cups, being the team MOP 5 times, and leading in career all-purpose yards.
1) Roberts - It would take a lot to bump Lewis off the top of this list, but 6 straight 1000+ and 4 straight 1500+ yard rushing seasons (only player to...) is my rationale for doing so. Unlike Reaves or Harris, who could generate 3-4 more yards after first contact on pure power, Roberts was the best ever at avoiding tackles for losses (which given his o-line, was an occurrence at least a half dozen times a game in some cases) by being untouchable. Still, he was able to fight for extra yards consistently when he was being wrapped up, despite his small stature. The Barry Sanders of the CFL, his rushing totals were more of an individual accomplishment than almost any other back. In an era when Khari Jones and Kevin Glenn each topped 5000 yards passing, and we had receivers like Bobby Gordon, Geroy Simon, Albert Johnson III, Milt Stegall, Terrance Edwards and Arland Bruce to name but a few, Roberts was still a superstar.