I don't think hes the best. I'd actually put McVay there, but he is still in the top 3. Winning 7 games without a passing game 2 years ago was pretty impressive
My list would be:
McVay
Reid
Belicheck
Harbaugh
McDermott
Tomlin
Lefluer
Shannahan
Reich
Vrabel
To your point about Vrabel, There are simply not many great coaches right now. He had a team, missing their best player for most of the season winning the number one seed in a very good AFC. He's a good coach. I think his biggest mistake this year was trying to run Henry so much in the playoff game. He was clearly rusty, go with what got you there