He is serious. He's as serious as those out there who think Dungy was a GREAT coach. I get flamed here in Indy when I suggest Dungy kept the Colts from more success rather than helped us achieve success.
IMO the ratio of player to coaching impact within the game itself is 80/20 players to coach. So, when the coaches control 20% and then fail at that, it is the difference between winning in the regular season and winning in the playoffs. It's a razor thin margin, the difference between winning and losing in most cases.
The HC has maybe 10 chances within a game to make impactful decisions. Fox (and Dungy, Lovie, etc) failed on about half of those 10. That's what makes a loss.
Not all decisions work out, case in point Belichick going for it on 4th and 2 and not making it against the Colts. But, I believe most fans would prefer the coach that has the fortitude to try.
So, in-game coaching makes up 20% of the game, and bad in-game coaches blow 50% of their decisions, and this is why John Fox, Tony Dungy, and Lovie Smith lose so much (I'm presuming you mean especially in the playoffs, because I've seen this argument before, and people usually assert it goes double in the playoffs). Let's examine your theory and see if it holds water. John Fox has taken over two TERRIBLE franchises (Carolina had the #1 pick and Denver the #2 pick when Fox was hired). Also, in his last season in Carolina, his owner was busy purging the roster in preparation for the lockout/new CBA, setting Fox up for failure. Despite this, Fox has a 94-82 career record (92-68, .575 discounting his last year in Carolina). His playoff résumé includes a winning career record, two NFCCG appearances, and a SB appearance- all with Jake Delhomme at QB- and a win with Tebow at the helm.
Tony Dungy is 139-69 lifetime, despite taking over the biggest laughingstock franchise in history, guiding them to their first sustained success. His 70 games above .500 are the 9th best total in NFL history. While he has a losing career playoff record (9-10), he does have a SB title and an NFCCG appearance with Shaun King (as a rookie).
Lovie Smith is 81-63 lifetime, with a SB appearance with Rex Grossman at QB, and a second NfCCG appearance (which might have been another SB had Cutler not gotten injured).
The three coaches that
you specifically mentioned have combined for a ridiculous 314 wins (vs 214 losses, for a combined .595 winning percentage), and are 18-18 lifetime in the playoffs with 3 SB appearances (1-2 record) and 7 championship game appearances (3-4 record). And these are the guys that you are specifically naming to prove that... What, conservative coaching leads to losses? Their record suggests otherwise. That conservative coaching leads to poor results in the playoffs? Again, their record suggests otherwise. That a conservative coach can't win a title? If his QB is Grossman or Delhomme, that's true. If his QB is Peyton Manning, that's false. Who is John Fox's QB again?
I will say it again- in-game decision making is really such a small part of a head coach's job, which is why those three gentlemen (and Andy Reid, the patron saint of terrible in-game management, and Bill Cowher, the patron saint of conservative play calling) have been able to be so consistently successful over their careers. It's why a guy like Marty Schottenheimer can make a 21 year career out of taking over terrible teams and only post a losing record 3 times. There is so unbelievably much more to coaching than just deciding when to go for it and when to kneel. Someone can be absolutely rubbish at history and still get a 3.5 GPA. He can't get a 4.0, but how many 4.0-type coaches are out there? Maybe 5? And they all seem to have jobs right now. If you can't get a 4.0-GPA coach, though, you could do a hell of a lot worse (and not a whole lot better) than one of the 3.5 guys. As I keep saying, in-game management is the most visible aspect of coaching, so casual fans think that's all there is to it, but the amazing careers that have been carved out by some terrible in-game guys demonstrates just how wrong that is.