Over the last five years, the single most difficult part of my job has been predicting what lineup and formation Jurgen Klinsmann will use for the US men's national team. Part of that is because of his cavalier attitude toward positions (anyone can play left back!) and seeming eagerness to switch from one formation to another on a game-by-game basis. Calling a Klinsmann lineup correctly was usually about as likely as tossing a dart, blindfolded, and hitting a bull's eye.

Then this summer, the most unpredictable thing of all happened: Klinsmann became predictable. He started playing the vast majority of his players in their correct spots; he scrapped one mostly-sensible-but-not-really-working lineup and formation (the 4-3-3) for another sensible look that actually worked (a 4-1-3-2/4-3-1-2), and stuck with it; he played his best players in their best positions and let them build chemistry and continuity, which mostly showed in the results.

Now, as I write this column, I am left to ponder whether I should predict that Klinsmann will once again be predictable, or if he will be be predictably unpredictable, as precedent would suggest.

And I have to multiply that by one Juan Carlos Osorio, an unrepentant tinkerer, ahead of Friday's qualifier between the US and Mexico (7:45 pm ET; FS1 & Univision) at Mapfre Stadium.

So please go ahead and take everything below with a grain of salt, OK?

PROBABLE LINEUPS

USMNT (4-4-2): Tim Howard; Fabian Johnson, John Brooks, Omar Gonzalez, DeAndre Yedlin; Christian Pulisic, Jermaine Jones, Michael Bradley, Alejandro Bedoya; Jozy Altidore, Bobby Wood

Mexico (3-3-3-1): Alfredo Talavera; Carlos Salcedo, Diego Reyes, Hector Moreno; Hector Herrera, Rafa Marquez, Andres Guardado; Giovani dos Santos, Marco Fabian, Raul Jimenez; Javier "Chicharito" Hernandez

I wrote about why I think the US will play a 4-4-2 yesterday. I think Mexico, meanwhile, will play a 3-3-3-1 (can we just call it a 3-6-1, please?) instead of a 4-3-3 because Osorio favors a three-man backline against any team that plays with two true forwards.

But, as always with these two coaches ...

The inexplicable is entirely within the realm of possibility.

• Can the US spine stay intact?

Much of the US success at this summer's Copa America came from the triangle of Brooks, Geoff Cameron (center backs) and Bradley (d-mid). That provided a level of stability that every team the US faced had trouble breaking down, and the one game in which the US moved away from that 4-1-3-2 (Argentina) they got annihilated.

Well, Cameron's hurt, which is a huge blow. And the other worry is the likely Bradley/Jones pairing in central midfield -- since Jones' laissez-faire approach to positional prescription has often forced 4-4-2's to become too spread out, or 4-1-3-2's to become too flat.

To put it another way: If Bradley is busy covering for one of Jones' forays, he won't be busy protecting the central defense. And the US central defense has always, always needed a dedicated d-mid in that spot.

• Mexico's results have been good, but their form has been spotty

The only thing that really matters are the numbers on the scoreboard after 90 minutes. We wouldn't be here, though, if looking into how those numbers came about wasn't an essential part of enjoying the game.

And for Mexico, the story has been one of inconsistency and dysfunction in terms of generating chances. This was on display in their last two friendlies (one-goal wins over Panama and New Zealand), and their their final qualifier (a scoreless home draw against Honduras), and even a little bit in their 3-1 win over El Salvador in the game before that.

The good news from El Tri's perspective is that the defensive frailties that were exposed and ruthlessly exploited in this summer's Copa America seem to have been at least a little bit submerged. Everyone remembers the 7-0 loss to Chile, but do you remember how many breakaways Mexico conceded to Venezuela and Jamaica in the two games leading up to that one?

Here are two paragraphs I wrote the day before the loss to Chile:

And by the way, Mexico still gave up a bunch of counterattacks against Venezuela. It's no more clear than it was three weeks ago what their best XI is, and the point of tournament play is to improve as the tournament goes along.

Now imagine it's Chile's Alexis Sanchez leading those breaks instead of the likes of Donaldson or Yonathan Del Valle. (Note: It will almost certainly be Alexis Sanchez leading those counterattacks in the quarterfinals). That is terrifying.

Is that weakness still present for Mexico? Tough to tell, since none of the teams they've played since the Chile game have had enough attacking firepower to punish El Tri, but given how loose and dysfunctional Osorio's teams tend to be against better quality competition ... I'm going to guess the US will have a few chances to run out.

• Can the US use their width without conceding counters of their own?

The US are orders of magnitude more dangerous when they get at least one fullback pushing up on the overlap, but doing so requires two things: adequate cover in behind, and ball security through the midfield. If the US are loose with the ball, any overlap from Johnson (likely starter at LB) or Yedlin (who I think -- but wouldn't stake my life on it -- starts at right back) is an invitation for Mexico to counter into that space, pull the US central defense wide and open lanes for Chicharito to dart into.

Another way of reading this is "turnovers are a big deal," which ... duh. But there's a specific way the US are vulnerable on turnovers, and a specific way Mexico have punished them over the years.

What's it all mean?

There are so many known unknowns here, but damn if I don't really like this lineup just based upon raw talent and toughness:

I'd also happily see Sacha Kljestan in that central midfield role in place of Jones, who may not be fit to go from the start given his summer-long injury followed by a sudden return and heavy workload for the Rapids. Kljestan has played in this qualifier before, has a symbiotic relationship with Bradley, and seemed to have instant chemistry with Pulisic when they set foot on the field together against Trinidad & Tobago back in September.

Regardless, this will be a game that requires a certain amount of opportunism from the US, who aren't likely to have all that much of the ball (true in any formation, but especially in the 4-4-2). If they can play directly to Altidore's feet in spaces where he can send Wood or Pulisic through, things bode well.

If not, get ready for a lot of long balls, a lot of running, and a decent possibility that the dos-a-cero streak will be consigned to the dustbin of history. Mexico are more than talented enough to make that happen, and both teams know it.