Way back in May, our own Devin Pleuler took a look at the Portland Timbers, who were in the midst of a long unbeaten run that would eventually stretch to 15 games.

Devin's conclusion was simple: It was unlikely, at that time, that the Timbers were simply "an exceptionally lucky average team." The numbers said they were very good.

Of course, Portland went on to give more strength to the numbers, finishing the season atop the West and on another long unbeaten run. This one stretched to 10 games, including the regular season and playoffs, and only came to an end two weeks ago in the high desert of Utah.

Let's start our tactical lookahead to Sunday's Western Conference Championship second leg there:

#WatchThis: POR-RSL 9 pm ET; ESPN, ESPN Deportes

What does luck have to do with it?

Not much, right? Both Portland and Real Salt Lake are exceptional teams, easily deserving to be here.

But it's fairly inexplicable just how much RSL have dominated the series this year. Across all competitions, they're 3-0-2, having outscored Portland 13-8.

To put it another way: In the five games against RSL, Portland have lost three times. In the 35 games against everyone else, they've lost four times.

It's not luck. Jason Kreis has figured Portland out to a good extent, and has capitalized by shifting his point of attack out of the middle and over to the flanks. Javier Morales drifted all over the field in RSL's 4-2 first-leg win, a game in which Kreis was actually happy to concede the middle:

That's 37 completed passes in that zone for RSL. Now compare it to the Seattle Sounders, who forced the issue against Portland in both the first and second legs of their 5-3 aggregate loss in the Western Conference Semifinals:

More than 100 completed passes in the middle in Leg 1:

And more than 100, once again, in Leg 2:

Portland's plan against most teams – really, against everyone – is to cut the field in half defensively and make whoever they're facing play down blind alleys. If you start on the left, you stay on the left until they turn you over. If you start on the right, you stay on the right.

And if you get to the middle, you're playing into their hands because that's where both Diego Chara and Will Johnson force the most turnovers.

RSL don't even mind, though. They're so technical and well drilled that they can go down one of those blind alleys, then either get the fullback on the overlap to whip in a cross, or move the ball into space and open up the field:

Everything in the play in the above GIF seems to be playing into Portland's hands – excellent shape and containment, and a real numbers advantage.

RSL turned it into a look anyway. And they've been doing the same all year against the Timbers.

It's a real question for Caleb Porter, one he has to find an answer to on Sunday if he's to have any hope of getting his team out of their two-goal deficit.

Putting pressure on the RSL central defense

If Houston's Rico Clark was the single most influential player in his team's playoff run, then Chris Schuler ran him a close No. 2. Schuler has changed RSL from a team that could only really defend well with the ball to one that has a lot of answers when playing back-foot defense.

He's become very, very good at reading off-the-ball runs, and gets himself into spots where he can put out most fires before they happen. And even when he's a step late, he scrambles exceptionally well – as the Galaxy learned in RSL's 2-1 aggregate win:

That's a hell of a play, one that he actually read early. You can also see that Schuler didn't quite account for Landon Donovan's quickness, and so had to make that last-second lunge, which he pulled off with aplomb.

And of course Kyle Beckerman was there to clean up the loose ball. RSL have gotten this down to a science over the last month, as their defensive interventions against Portland in the first leg show:

That is ridiculous balance and symmetry. The three of them are operating as a true unit, and Portland's best chance of pulling back on that two-goal deficit is to break them apart.

Enter Maximiliano Urruti.

The Argentine is something of a flashpoint amongst the Timbers faithful, and a spate of late-season injuries have prevented him from showing his full value.

He's not listed on the injury report, but it's a stretch to imagine he's in Porter's XI from the start – he's just been sidelined for too long. But this is an example of what you want to bring into the game late, when high pressure can be the most effective:

My guess is that Ryan Johnson starts the game for Portland, since he's been the best at holding the ball up and bringing the rest of the attack into the play. But come the 60th minute, expect Urruti to be in there and break some of that symmetry that's served RSL so well.

A few other notes:

• Diego Valeri really hasn't been fit since early in the season, and trained only sporadically over the two-week break, but he should be good to go for this one. He's not listed on the injury report, which is an obvious "good thing" for the home team.

• Alvaro Saborio is listed on the injury report, and won't play in this one. That means rookie Devon Sandoval will get (another) start, and that might not be a bad thing for RSL. A few bloggers have crunched the numbers, and they look very good.

That said, Sandoval is nowhere near the aerial presence Saborio is. Sabo won 44 percent of his aerials this year, while Sandoval won just under 27 percent of his. If Portland force RSL to take the high road, the field could very well tip towards Nick Rimando's net. Sandoval needs the ball played to feet.

• No Chris Wingert for the visitors. This hurts in terms of possession more than in attack or defense, where Lovel Palmer has done pretty well this year.

• Set pieces. (This is boring, I know). RSL have annihilated Portland on set pieces all year, including in the first leg. Whatever it is that happens from the run of play won't matter at all if the Timbers can't figure that one out.