"My contention is that when teams win they are usually considered tough and when teams lose the fans and press question their toughness. I think talent and strength is mistaken for toughness. "- Ziff72
To me, "toughness" is being able to overcome adversity and not lose track of the point of it all. I would say that teams who win despite a schedule and circumstances which stack up against them by conventional wisdom display "toughness" to a degree. Individuals who perform at a position where they were not expected to be much display "toughness". To a great extent, I do believe you are right - some teams are simply more talented and stronger than the other team they are playing, and the physically bigger team will likely win, but it doesn't necessarily speak to how "tough" the loser in that contest may be.