Just as we observe aging athletes miss the open receiver a little bit more often or are a tad slower with their 'reads', it's important to remember that aging has cognitive implications as well. And like physical aging, they are likely to be subtle.
I'm not saying Belichick has 'lost it'. I'm saying that EVERYONE 'loses it' gradually over time. Little by little, our decision making is worse than our younger, better selves. Something to pay attention to.....in coaches and owners alike.