On the surface, it appears that the NFL and Major League Baseball spent nearly the same amount of money on free agents this off-season, with teams from both leagues dishing out contracts worth in excess of $2 billion. But that spending looks a lot different if we consider the true value of the deals.
In the NFL, only 38.7% of the $2.0 billion in free contracts is actually guaranteed. In contrast, 92.2% of the $2.4 billion spent on MLB free agents is guaranteed.
On top of that, if we consider that there were nearly twice as many NFL free agents (274 vs 140), it becomes clear that the total amount spent is not nearly as similar as it appears.
Data via MLBTraderumors.com, BaseballProspectus.com, and Spotrac.com