Source: Sanchez deal has $20.5 million in real guarantees

I resisted repeating any of the various reports that emerged last night regarding Mark Sanchez’s new contract because the word “guarantee” was being thrown around casually, like it was when Donovan McNabb got $40 million guaranteed from the Redskins in 2010 — and the truth was that he got only $3.5 million. Per a source…