Tonight is why we do this. Games 5 and 6 of this epic Western Conference finals between the Golden State Warriors and Oklahoma City Thunder represented peak playoff basketball -- the perfect mix of beauty and grime. Watching a team play beautiful basketball for 48 minutes brings us close to euphoria, but it also means that team is humming -- that it can exist constantly as the best version of itself. Life is easy.

In those two fingers-digging-into-the-armrest battles, neither team let the other reach that state. The strategies that got them this far were no longer good enough. When that happens, a team can either quake or search deeper for new ways to win. The Warriors and Thunder cut harder, tested the limits of shot-making against unyielding defenses, invented new tricks and played beyond exhaustion.

It was raw, improvisational and a little dirty. Only championship-level teams can impose that sort of degradation, and only championship-level teams can adapt well enough to survive it.

Whatever happens Monday tonight, both teams have proved their championship mettle. The Warriors are favorites, because the Warriors are at home, but you cannot possibly have watched this Thunder team rise over the past three weeks and expect them to lie down after a defeat that might leave a lesser team hollow.

Here are five things to watch in a game that everyone outside Oklahoma City wanted:

The Iguodala question

Warriors coach Steve Kerr made the first dramatic lineup change of the series by starting swingman Andre Iguodala over Harrison Barnes in the second half of Game 6, and with a historic 73-win regular season on the line once more, Kerr should consider doing it from tipoff. Iguodala has outplayed Barnes, and he is a better fit for this matchup. Editor's Picks How to bet Warriors-Thunder Game 7

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Barnes' best asset on defense is his ability to credibly defend big men on the block, and aside from a few random Enes Kanter post-ups, that just doesn't mean much in this series. Barnes is a little mechanical guarding Thunder forward Kevin Durant; he reacts to each move, lurching after him from a standstill once Durant starts a cut. Iguodala is fluid. He moves in tandem with Durant, mirroring him almost stride for stride with a genius sense of anticipation.

On offense, Iguodala's secondary ball-handling is probably more important against Oklahoma City than Barnes' 3-point shooting. When the Thunder strangle a possession by switching everything, Iguodala is better equipped to create something from nothing off the bounce. He's in another universe as a passer; Barnes has missed several wide-open shots in this series.

The Thunder hide extra big men on both Iguodala and Barnes, and the Warriors have responded by having those guys screen for point guard Stephen Curry -- a method of dragging Thunder behemoths into the Curry-centric action they'd prefer to avoid.

The Thunder will usually trap Curry in that circumstance, yielding a free roll to the rim for Iguodala or Barnes. They in effect become big man Draymond Green, running the 4-on-3s that fuel Golden State in happier times. Iguodala is a more natural drive-and-kick Green facsimile.

Golden State's starting lineup has outperformed the version with Iguodala in Barnes's place over the full series (though not the full season), but Iguodala is more comfortable than Barnes coming off the bench. Perhaps Kerr will stick with the regular starters, but be ready to insert Iguodala earlier.

On staggering, and centers

The Thunder are plus-45 in the 206 minutes Durant and point guard Russell Westbrook have played together and a disastrous minus-30 in the leftover 82 minutes, per NBA.com. They shared the floor for 41 minutes in Game 6, a series high, and unless coach Billy Donovan abandons the staggering gambit, it is impossible for them to play much more than that.

Oklahoma City has mostly gone small with Durant on the bench, and jumbo -- with a Durant, Steven Adams, Kanter frontcourt -- when he plays without Westbrook. Nothing has really worked.

Kerr loves to chance it by starting the second quarter without Klay Thompson, Curry, or Green on the floor, and the Warriors' offense flatlined for that chunk of Game 6. They couldn't gain any north-south traction; no Warrior could beat his man one-on-one, reducing every possession to a series of harmless pitches around the perimeter.

Golden State is almost impossible to beat when it wins these games within the game. The Warriors rely on tough shots: Shaun Livingston post-ups, random Marreese Speights outbursts and Barnes pull-up shots over bigger guys. The Thunder have made those shots even tougher. Shooting guard Dion Waiters has morphed into The Thing walling off Livingston's post-ups.

As he often does in close games, Kerr adjusted by pulling Thompson a hair earlier in the third quarter so that Golden State could start him (and Green) in the fourth quarter. If the Warriors are behind, Kerr should probably go this direction in the second quarter Monday.

The center minutes alone will be fascinating to watch. Adams has been sensational for Oklahoma City the entire playoffs, tailor-made by the basketball gods to slip into the void and gobble up offensive rebounds when defenses overload on the Thunder stars. When Durant has his pocket-pass game on, Adams is a legit pick-and-roll threat. Golden State's centers have to scurry around the 3-point arc to quash Durant's off-the-bounce triple, and if Durant looks for it early, he can find little creases to spring Adams:

Adams has held steady on defense, even against the Resurrected Lineup.

But Golden State's small-ball group finally hurt Adams a bit down the stretch of Game 6, and spacing can get tight when Adams and Andre Roberson share the floor -- especially when the Thunder stand still around their superstars:

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Donovan hit the jackpot in Game 3 using a smaller lineup with Serge Ibaka at center that can absorb Roberson's non-shooting without choking the offense. Finding the right balance in the heat of the moment is hard and will depend a lot on what buttons Kerr pushes.

On the other side, it's hard to imagine Golden State winning again if it gets zilch from its four centers. Doing so required a historic long-range performance even the Warriors would be hard-pressed to replicate. The Death Lineup experienced a rebirth, as ESPN's Kevin Arnovitz and I predicted it would in our Friday podcast, but overdoing it risks foul trouble and obliteration on the glass. Andrew Bogut's defense at the rim has been essential, especially against Westbrook, who has to choose between midrange jumpers with Thompson on his hip or blind rushes into Bogut's monster frame.

If the Warriors play a traditional center, the Thunder are more likely to play one, too, and Golden State has found some success having its biggest players screen for Curry:

The Warriors know the Thunder don't want to switch Adams onto Curry, and that a Curry-Bogut pick-and-roll can produce a Frankenstein-speed version of the old Green 4-on-3 plays. The Thunder have been late helping on Bogut and Festus Ezeli around the basket, perhaps reasoning Curry won't be able to find passing angles through that thicket of long Thunder arms.

And, man, could the Warriors use some easy buckets at the rim. They have hit just 53 percent in the restricted area, a mark that would have ranked last in the regular season. The Thunder are completely in the Warriors' heads: Golden State is passing up layups, spinning away from phantoms at the basket and spooking themselves into high-risk drive-and-kick madness when easier stuff is staring them in the face:

These "plays of insanity," as Kerr has called them, sabotage the Warriors' offense and ignite the Thunder's "Mad Max: Fury Road" transition game. Golden State took a ton of flak for jacking too many "quick shots" earlier in the series, but not all quick shots are the same. A catch-and-fire Thompson 3-point attempt ahead of the action, with the other four Warriors prepped for quick offense-to-defense turnaround, is fine. A desperate pass or heave with the floor unbalanced is fatal.

Speaking of centers: Can Golden State spring Curry again?

The Warriors got more creative engineering open looks for Curry in Game 6, usually by involving Oklahoma City's big men in the Curry ballet. Curry scrunched through two- and three-man mazes that almost always included Bogut -- games of hide-and-seek that made it hard for the switch-happy Thunder to keep track of who had Curry duty:

When Oklahoma City's bigs contained Curry on the first action, he was more diligent about giving up the ball, running around some more and getting it back:

Curry found open water by faking toward a Bogut pick, knowing Adams would rush to meet him on the other side and then veering back the other way:

Part of that was Westbrook backsliding into hopping madness after playing pretty sound defense for most of the series. Guarding Curry for this long takes a mental toll. It is hard to be hyper-attentive against the greatest shooter ever, in constant motion, over and over for two weeks.

Westbrook exhaled occasionally when Curry gave up the ball, and the Warriors pounced in smart ways -- including on this brilliant little play from Green, who sets a pick for Curry, reads the usual Thunder switch and appears to laze into post position before bolting back up for another pick:

Westbrook will have to be better tonight. If he is, the Warriors must stretch the boundaries of their imagination further.

Can Oklahoma City avoid prevent mode?

Oklahoma City's offense is going to be predictable. It's just in the Thunder's DNA. There is a fine line where it becomes too predictable to function against elite defenses, and the Thunder crossed it during a hideous fourth quarter with a trip to the Finals in their grasp.

Defenses are always going to send extra defenders toward Durant and Westbrook, leaving other guys open across the floor. It is a naked bet against the Thunder making a single productive pass, even though both superstars are capable.

The Thunder melted down in Game 6, running the same sets they always run. It was more about when they ran them, and what was happening away from the ball. When you walk the ball up the floor, do literally nothing for five more seconds and finally go into some action the whole world can see coming, you don't even have time to make another pass:

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With five seconds left on the shot clock, the Warriors have already won their bet: Durant won't pass, and with that knowledge, the Warriors can send even more bodies toward him -- and toward the glass. It gets even easier when the other four Thunder players are stacked next to each other in pairs, standing still, so that one Warrior can defend two of them.

This is Basketball 101, and the Thunder have been studying it now for five-plus years. Start your work earlier, keep bodies in motion off the ball and you can whip it cross-court into looks like this -- on an action where Durant is already primed to attack a switch with 17 on the shot clock:

The Warriors probably panicked into sending too much help too early on that play, but that's exactly the kind of panic the Thunder induce when they don't chill with the ball for the first 15 seconds of every possession.

Who wins the battle of chaos points?

The Thunder have been careful getting back on defense, even as they've amped up their own offensive rebounding. Having Ibaka, a rim-protecting menace, stationed above the 3-point arc on offense helps; he's often the first guy back, and both Adams and Durant have been busting it right behind him. Those six long arms are turning what look like clean on-the-run layups into contortions that have mostly rolled out.

But Oklahoma City finally broke apart a bit in Game 6. It failed to locate Curry a few times even when the Warriors had no numbers advantage -- including on the Curry bomb that tied the game late in the fourth quarter. When it felt like the game was on the verge of getting away from Golden State in the second quarter, the Warriors snagged a 3-on-1 bucket when four Thunder players hung near the baseline on a Waiters miss from the corner:

You can't give the Warriors scramble points like this when your half-court defense is smothering them; the Thunder need to keep their floor balance in check, especially when Westbrook is chasing offensive boards.

Offensive rebounding is a core part of the Thunder's identity. They rebounded more of their own misses than anyone this season, and the gap between their mark and the No. 2 team was the largest in league history. They have sniffed that season-long norm over the past four games after the Warriors held them at bay during the first two.

Adams and Roberson crash when the defense ignores them, and Westbrook might be the most tenacious offensive rebounding guard in league history. The Warriors are reluctant to switch even Green onto him; Westbrook has torched Green off the dribble, and sending Green to the perimeter removes him from the rebounding scrum. (Watch for the Warriors to try and force Westbrook to his right, by the way).

Westbrook will snare some random boards only he would get, and if he can optimize the pursuit so that it doesn't submarine the Thunder's transition defense at the wrong moments, Oklahoma City will have won one of those games within the game. There is not much to plan for either way. Westbrook is a human chaos engine.

The Thunder's other offensive boards emerge organically from the structure of their offense, and the Warriors have to do a better job containing those. Adams feasts after setting ball screens for Durant and Westbrook, watching his man drop away to contain them and slicing into abandoned territory for second chances:

On plays like that, someone -- probably Barnes, in this instance -- needs to slam Adams as he crosses the foul line.

Every grubby, sweaty, pointy-elbowed thing matters now. This is Game 7, baby! The spectacular stuff matters, too, of course. Thompson, Curry and Durant will make a certain number of preposterous long jumpers. Westbrook will can some of those flailing mid-rangers over Bogut. Great players make tough shots. The team whose great players make more of those tough shots will probably win tonight .

But all of the little battles surrounding the spectacular ones matter, too. There is no more margin for error. Let's sit back and drink in another epic. Cleveland awaits.