 This occurrence is sometimes seen in MLB, but it is almost never found in the NFL due to the league's relatively low salaries and most importantly, the lack of guaranteed contracts.NFL players who sign contracts with new teams and then don't perform can simply be released from their team, as the team is then only held responsible for the bonuses in the contract.Recent MLB studies do find evidence of the contract year boosting a free agent hitter's On-Base-Plus-Slugging Percentage (OPS) by 4-6%.