You can easily make the argument Matthew Stafford + Calvin Johnson = the best passer and receiver duo in the entire league, but the real question is will this pair ever be enough to reach the Superbowl (much less win one) alone? The Detroit Lions offensive line is average-to-above-average, giving Stafford plenty of time to throw and often finding his go-to guy in Megatron, but without a respectable running game, I question the Lions ability to do damage in the post season.
I can easily see these two guys shattering records if they spend their entire careers together, but what's the real value in regular season passing/receiving records if there's no Superbowl rings to complement? I'm willing to bet your average NFL fan couldn't tell you the name of Detroit's #1 option running back, but surely the average NFL fan could tell you there was once a Lions RB who is commonly considered one of the greatest of all time.
Perhaps Barry Sanders isn't regarded as the surefire GOAT at the position, as most would give that honor to the legend (who's picture above Sanders) who played for the team he shared his own last name with, but you'd be ill-founded to make an argument Mr. Mighty Mite outside of any Top 3 of all time argument. He proved it doesn't take sheer size and strength to dominate the position; and that it's more about heart and raw determination.
American's favorite sport is often referred to as the "not for long" league. At one time the Lions possessed the league's best running back. Now they possess the league's greatest receiver, and one of the best quarterbacks with quite possibly the strongest arm. These two guys are going to certainly entertain as long as they're healthy in this new era pass-happy league. I do however question their (the Lions) ability to damage teams in the playoffs and question if and when they'll ever make a Superbowl or win one - without a respectable running game.