But you can't ignore the fact that guys like Harden, Durant, and Westbrook became All-Star caliber players under his watch, and Ibaka became a defensive powerhouse. Brooks has to get some credit for that. His offensive playbook could use some development, but that's not the only quality of a coach. Managing egos, figuring out what rotations to use, developing players: that's all part of it.
I also can't ignore the fact that they ALL would be better right now, if they had a better coach that utilized their talents properly. Ibaka isn't a defensive-powerhouse, his blocking ability (natural talent) is why he's a defensive threat, take away that and he does nothing fundamentally 'great' on the defensive end. His offensive-playbook doesn't need any development, simply because he doesn't have one. There's no structure to the offense, its basis is all isolation. Minimal - ball movement, off-ball movement, pin/flare screens etc etc. Without Westbrook/Durant-caliber type players - the offensive-system would be looking like one of the worst in the league.
Brooks' offense is closer to the Bobcats than the Heat's.
If those are the qualities of good coach (managing egos, figuring out what rotations to use, developing players) it's clear that Brooks isn't even close to a good coach.
And when they went down 0-2 to the Spurs, a veteran team with THE best coach in the league, you can't tell me Brooks had no part in turning that series around. Plus, it's extremely rare that a team with such a young core makes it to the NBA Finals, no matter how much talent they had. Remember when they made it to the WCF the year before, and Westbrook was

'n every damn game? You don't think Brooks had a hand in getting him to cool that shyt out?
When was the last time a squad had THREE 20+ point wing scorers on its team? The Thunder got there purely on talent, obviously not ENTIRELY - but it all revolved around the star players' natural abilities.
Westbrook

'd just the same, only difference is he limited his turnovers and shot at a higher %:
10/11 playoffs he averaged 20.2 shots per game at 39% averaging 23.8 PPG (4.6 turnovers)
11/12 playoffs he averaged 20.4 shots per game at 43% averaging 23.1 PPG (2.3 turnovers).
There a number of things that swung in the Thunder's favor after that 2nd game: Ginobili averaged 23 PPG in the first 2 games then dipped down to 10 PPG over the next 2 games, Pop fukked up his rotations, Ibaka had 4 made field goals in the first 2 games - then had 24 made field goals over the next 4 games etc etc. Once OKC built a lil' momentum from their homes wins, the Spurs found it hard to dictate the pace (the advantage they previously had over the Thunder) over the rest of the series.