Did Emmit have anyone drafted higher than the 3rd round on his OL? Did Emmit have castoffs from other teams on his OL? Are any of Emmits great wall on the HOF? They were great as a unit. They had great coaching. But lets not act like they were 5 blue chippers. Other guys ran behind this same OL when Emmit was out....and did not look like a HOFer. And Emmit also blocked and caught passes. Emmit also got a steady 4+ yards. Emmit was savage around the goaline and in short yardage. Barry was electric....but give me Emmit all day. And during Barrys prime...the Lions had the highest paid OL in the league.
I've never understood that line of reasoning about the OLs either. I do think that there was an advantage to Emmitt in that regard...but, not the overwhelming advantage perceived by some due to the persistent myth the Emmitt played behind a solid, impenetrable wall for his entire career, while poor Barry had to make due with cast offs from the Detroit-area high s hooligans JV teams. Barry had an above average line for several years...probably a very good one for 2-4 years of his career depending on who is making the evaluation. Emmitt just happened to have an All-World one in roughly the same time frame in the early 90s. But, over their careers, I think that Detroit may have had roughly equivalent OLs to Dallas...maybe even slightly better ones here or there going into the late 90s. Again, on the whole, probably still slight advantage to Emmitt, but not so much of one that you can explain away his success vis-a-vis Barry.
There is also one thing that ALWAYS gets overlooked in this comparison. Barry played in an offensive system (for much of his career...maybe all of it?) that all but prevented opponents from stacking the box. The Run and Shoot offense Detroit used in that era meant that a LOT of DBs were on the field AND spread out wide to cover the WRs. There weren't a lot of 8 and 9 man fronts that Barry had to face, whereas Emmitt did. Granted, that means that Emmitt had a FB in front of him that Barry wouldn't have. But, I think that the offense Detroit ran is an often overlooked factor in the comparison.
I've always actually maintened that both backs were in the best situation possible for each of them. I don't think Emmitt would have thrived like Barry without a FB consistently in front of as part of a system that allowed him to make use of his vision, instincts, and alight advantage in power (as compared to Sanders). I don't know that Barry would have been able to put his agility and evasiveness to as good a use in the offense that Dallas ran. I sometimes wonder if Barry wouldn't have ended up being injured, or hampered by the wear and tear even if not on IR, being hit a bit more often by people who are a bit bigger, a bit stronger, weigh bit more, and who put just a bit more pride/emphasis in/on their tackling. Getting whacked Junior Seau, or any linebacker, was probably a different experience than being hit by a CB (or even most safeties). Once makes little to no difference. One hundred times, you may start to notice a difference. A few thousand times over the course of a career, and it adds up. Barry with 5% less agility, a tenth off his 40, or any other subtle results of that phenomenon might have a made big difference...whether in year 6 of his career, in games 13 through 16 for all of it, or both.