It's because we haven't gotten one that is good enough to make adjustments once DC's figure them out in year 1. It's why the first year Bills go 13 wins and look amazing and 2nd year they go 11 wins and it's way too much of a struggle. It's happened three times in a row now (assuming Bills get to 11 wins which I am guessing is a good bet). If Brady gets fired or gets a HC job, we should not be surprised if the new guy coming in gets us back to 13 wins again in year 1...it's what happens in year 2 that matters to determine if we have a guy that can actually be more than a 1 year wonder.