You can argue that just about every year in the NFL is a contract year. The only players with more than two years of job security are rookie first-round picks and true upper-echelon superstars. Most free-agent deals these days are for two years of guarantees with team options afterward, and even those guys are the exceptions to the rule. Such is life in a league with nonguaranteed contracts.
With so many players operating year to year and the average career being shorter than any other major U.S. sport, each individual season is more important for a football player than it is for players elsewhere.