This is all great, but the point is he was a head coach for 12 seasons.
Right now here is the tenure of coaches and their winning percentages who were hired before 2010.
BB - 15 years - .73 (damn) HOF: TB12, (aka GOAT), Gronk
Marvin Lewis - 12 years - .541 HOF: No one???
Mike McCarthy - 9 years - .653 HOF: Aaron Rodgers, maybe Clay Matthews
Sean Peyon - 9 years - .604 HOF: Drew Brees
Mike Tomlin - 8 years - .639 HOF: Big Ben, maybe James Harrison, maybe Hines Ward
John Harbaugh - 7 years - .602 HOF: Ed Reed, Ray Lewis, maybe Haloti Ngata, maybe Flacco
Tom Coughlin- 12 years - .531 HOF: maybe Eli? Probably Michael Strahan
So outside of Marvin Lewis who everyone thinks would have been fired at some point if not for his cheap owner, everyone has above an .604 winning percentage in their 7+ years with their current team.
Every other coach outside of these 6(!!) have been a head coach for 5 years or less. Coughlin's teams got hot at the right times to prevent him from getting fired, but a .531 win percentage over 12 years leads to an opinion of him not being a good head coach. Slightly out-performing basic statistics does not make him a good coach, it makes him a coach who would have been fired sooner if not for Justin Tuck and Good Eli.