I had a toss play with -2.2 yds/attempt. I canned it
Most toss plays suck because most CB's/LB's are faster than the pulling lineman and often blow the play up for a loss. My team's defense in Custom 79 often stuffs it for 5 and 6 yard losses but that's the extreme end of the spectrum, that defense is damn good.
The few times it is successful is usually a bad defensive alignment or a team has lineman fast enough to get out there and actually block that first guy along with a RB fast enough to get to the hole at the right time.
I have several very successful running games in MFN, just not in this league yet, and I used to have but 1 team I felt comfortable using that play, but that was also year 1 of a start up league and now defenses have caught up, it's scrapped. If your RB's are good enough and OL good enough, you can run for 150-200 yds a game or more without using any toss or sweep plays.