The Dallas Cowboys are one of the best teams in the NFL... in May, on paper. What matters the most is how you fare throughout the fall and winter. Rankings and projections are fun but nobody ever won the Super Bowl because somebody said that they would during the summer.
None of this is said to diminish the value of rankings and projections because they certainly have their place. We can look at educated guesses and estimations as to what teams like the Dallas Cowboys will accomplish in a given season and then hope that things play out along those lines.