As soon as news came out that Matthew Stafford agreed to a deal with the Lions, we found out that nearly $42 million of his contract was guaranteed. That figure was a record for guaranteed money, and as you can imagine, many were upset that he got such a big contract. Well, as it turns out, Stafford is only absolutely guaranteed to receive around $17 million. Chances are he will end up receiving most of the originally-reported $42 million, but there are incentives he has to achieve and an option for the 2014 season that has to be picked up by the Lions in order for that to happen. Technically, the money he could end up getting isn't actually guaranteed, but again, it is unlikely that he won't end up gettting it.
Why is there such a difference in what was originally reported compared to what we now know? Well, AdamJT13 put together a thorough breakdown of Stafford's contract that reveals just how complex an NFL contract is. Stafford's base salary over the years will change based on whether or not the Lions exercise his 2014 option and whether or not Stafford hits performance and playing time incentives. The qualifiers based on playing time don't have to be achieved in the first year. The performance-related incentives in the contract can change how much money Stafford makes, but it appears that the playing time qualifiers are more related to the $42 million figure.
This is all pretty complicated, but to put it in layman's terms, these qualifiers and the 2014 option basically protect the Lions in case Stafford turns out to be the bust of all busts. For Stafford to only receive $17 million, he would have to never meet his playing time incentives, not have his option picked up for the 2014 season, and be cut in 2013 (if I'm understanding this correctly). Busts at the quarterback position usually get a chance to play before they are actually declared a bust, which is why the guaranteed number has been reported to be $42 million. It would be surprising if Stafford didn't meet his playing time qualifiers, and I doubt the Lions will not pick up his 2014 option (they have to make a decision on the option in 2010).
Bust or not, down the road, chances are that Matthew Stafford will have received close to or all of the $42 million in his contract that is supposedly guaranteed. The thing is, it isn't really guaranteed. AdamJT13 believes that Tom Condon, Stafford's agent, wants to toot his own horn, so to speak, by leading everyone to believe there is nearly $42 million guaranteed in his client's deal. In reality, though, Stafford is only guaranteed to receive about $17 million. He probably will receive much more than that, but it is not truthful to say that Stafford is absolutely guaranteed to get $42 million out of his deal with the Lions.