But that's the contract as the NFLPA agreed to it. Guaranteed money is just that, guaranteed even if you suck. Unguaranteed salary is just that, not guaranteed. When these guys sign their deal they know up front what is and isn't guaranteed. In many cases they are being paid a % of the total contract value up front as part of the trade off. Trouble is many of them forget that (or have spent that) by the time the backend rolls around. While others aren't holding out for a deal per se so much as holding out for what the team may view as an unrealistic deal.
And the average career of an NFL player is 6 years. The numbers the association trumpeted during the lockout included any cup of coffee guy ever signed who never made a 53 man roster like all the UDFA's teams are trying out this TC season. The average pro bowler has a 9 year career.
And anyone recommending the NFL adopt any MLB rules is nuts...