If you're a US men's national team fan, then 2015 offered the winter of your discontent. There was the record-tying home winless streak against CONCACAF foes; the disappointing Gold Cup performance (both aesthetically and results-wise); the constant lineup tinkering; and the crystal-clear indication that Mexico have retaken the title of kings of CONCACAF.

So there weren't many highlights to choose from -- especially in the games that mattered. But in the friendlies the US played, there was often some fun to be found, especially on the two-game trip to Europe in late spring, when the US topped the Netherlands, 4-3, at the Amsterdam Arena, and then five days later beat Germany, 2-1,in Cologne.

The first US goal in that particular game came after a patient and penetrating 30-pass sequence that I've watched roughly 400 times over the last six months:

Alas, this form was not replicable in most of the games that mattered in 2015 as the US suffered their worst year of the third millennium. Let's start with the sad parts.

Formation and Fallacy

While the nature of the international game demands a certain amount of tactical flexibility, Jurgen Klinsmann's schizophrenic approach to choosing his lineups and formations was probably the defining characteristic of 2015.

Over the first four games of the year, the US trotted out four different looks: a 3-5-2 (loss to Chile), a 4-2-3-1 (win over Panama), a flat 4-4-2 (loss to Denmark) and a diamond 4-4-2 (draw vs. Switzerland).

At that point, Klinsmann decided the diamond was his preference, going with that formation for nine of the team's next 10 matches, with the win in Amsterdam (4-3-3) the only exception. That decision didn't pay off, as the US endured a disastrous Gold Cup performance, failing to adjust to various tactical gambits thrown at them by other CONCACAF teams: a) The US left huge gaps to exploit on the wings, and b) they struggled to avoid the types of costly turnovers that get punished by good counterattacking play.

Even with all of that evidence in front of him, Klinsmann stuck to his guns for the massive CONCACAF Cup against Mexico in October, which finished 3-2 to the Mexicans. (Frankly, the scoreline flattered the Americans.) The US started out in a diamond, and El Tri blew it apart in the first 10 minutes. The state of the game at that point was so lopsided that Klinsmann had to switch to a flat 4-4-2 to stem the bleeding.

The adjustment asked Jermaine Jones to play on the wing, Fabian Johnson to be a stay-at-home right back, and Kyle Beckerman to go box-to-box in central midfield. Those players are ill-suited to those roles. Which was another staple of 2015: Klinsmann's continued penchant for playing guys out of position.

A Stat That Matters

The US played seven official (non-friendly) games against CONCACAF teams ranked in the FIFA top 100 in 2015. They were outshot 122-69 in those games.

In analytics circles, of course, the sentiment is that total shots over the course of a game tends not to matter. But over a large enough sample size -- such as seven games -- Total Shot Ratio remains decently predictive. That's because over a long enough timeline, shot quality for and against tends to regress toward the mean. That makes shot volume is just as predictive as something a little more mathematically weighty, like expected goals.

Another way to look at it is like this: Giving up a lot of shots isn't a problem; it's a symptom. Taking very few shots isn't a problem; it's a symptom.

And for the US, the disease was a dysfunctional midfield born of constant tinkering and guys being played out of position. Michael Bradley is not a No. 10, Jones isn't a winger, Alejandro Bedoya is not a No. 6, and neither Gyasi Zardes nor DeAndre Yedlin is very effective on the sides of a diamond.

That type of dysfunction led to this statline against Mexico in the CONCACAF Cup:

Allowing an opponent to complete more than 90 percent of their passes in a game that truly matters, and allowing them to outshoot you by a significant margin (23-14), and allowing them to attempt 150 percent more attacking passes is clearly not good.

You may be able to win a one-off game like that -- the ball is round and anything can happen, right? -- but regularly prying good results out of that sort of mess is not sustainable. And in fact, the Americans' current run of results shows as much. They are now 0-4-2 in their last six games against CONCACAF teams ranked in the top 100.

That includes a loss to Jamaica and Panama en route to a fourth-place showing in the Gold Cup, the worst for the US since 2000. It also includes the CONCACAF Cup loss in which the Yanks were outplanned, outplayed and largely outclassed by a team that were themselves in turmoil.

So in this case, it turns out that total shot ratio was predictive. You could see this death spiral coming if you looked at the underlying data.

The Next Generation

Michael Bradley was named US Soccer's Male Player of the Year, and he was certainly the most important creative threat, even when played out of position and even with the rotating cast of characters around him.

But there are four guys on the rise that give US fans something to be optimistic about heading into 2016.

We'll start with Bobby Wood, the most accomplished of the bunch. The 23-year-old forward scored four times this past year, including late winners against Germany and the Netherlands, an extra-time equalizer against Mexico, and an early equalizer in November's World Cup qualifier against St. Vincent & the Grenadines. (Yes, the US actually trailed against St. Vincent & the Grenadines.)

He's kept that form going with his club team, Union Berlin, who are in Germany's second division, for whom he has seven goals in 19 appearances. Most promising of all is that Klinsmann so far refuses to play Wood out of position. he is a forward, and that's it. Refreshing.

Wood is six weeks too old for the US U-23s, who are in the last throes of Olympic qualifying, or we'd have seen much more of him playing together with Jordan Morris. Morris -- also exclusively used as a forward thus far -- became the first collegian in a quarter century to play a significant part with the full USMNT, and even got his first international goal in a 2-0 win over Mexico last spring. He led Stanford to the school's first College Cup title, and is widely expected to sign a pro contract -- the Seattle Sounders have dibs in MLS -- at some point this winter.

US Soccer's Young Player of the Year was New York Red Bulls center back Matt Miazga, and his rise was meteoric. He began 2015 third on his club's depth chart, and finished it, I'd argue, as one of the top five center backs in the entire league. Along the way he helped the US to the quarterfinals of the U-20 World Cup, became a fixture with the U-23s, and made his full national team debut in November's qualifiers. That cap-tied Miazga, who was also eligible to represent Poland thanks to his heritage.

Also cap-tied in November was Portland Timbers midfielder Darlington Nagbe, just months after finally earning citizenship. The Liberia-born Nagbe has been in the US since age 10, and his ability on the ball and explosion through the lines is just breathtaking:

No midfielder in US history has left defenders for dead like that, and moving Nagbe from the wing to central midfield is what changed Portland's season. They were below the red line in early October. Then head coach Caleb Porter shifted Nagbe inside, and the Timbers went on to win their final three regular-season games before steamrolling through the playoffs to win their first MLS Cup.

Of course, Klinsmann has used Nagbe more as a wide midfielder thus far. We'll see what happens with that in 2016.

The Old Guard?

While those are potential answers, there remains the typical surfeit of questions. As of now it's still not clear what the best US formation is. And there are a bunch of age-related personnel questions.

1) Is there a replacement for Kyle Beckerman? While the 33-year-old RSL stalwart has proved divisive among US fans, what isn't divisive is this: The US have historically been much, much better with a true No. 6 on the field. Danny Williams hasn't made the job his, while youngsters Wil Trapp and Perry Kitchen have played other positions in their caps. U-23s Matt Polster and Fatai Alashe may somehow figure into the mix soon, but so far Klinsmann appears to prefer to play the likes of Mix Diskerud or Alejandro Bedoya out of position rather than use a full-fledged d-mid.

That hasn't worked, and one of the year's absolute low points came in a 4-1 loss to Brazil when Bedoya -- learning a new position on the fly against one of the world's best teams -- was yanked after 40 minutes. Klinsmann added insult to injury by calling Bedoya out in the press afterward. Not a good look.

2) Is Fabian Johnson a winger now and forever? Klinsmann has long overlooked Johnson's defensive failings (think of the late goals by Ghana and Portugal at the World Cup) and preferred to use him as a fullback. This may have led to another public falling out, this time after the CONCACAF Cup in which Johnson asked to be subbed in extra time, and Klinsmann very publicly sent him home for an alleged lack of commitment.

So it was something of a shock when Johnson came back the following month for World Cup qualifiers, and perhaps a bit of an unspoken mea culpa on Klinsi's part when he started Johnson on the wing. A good move, considering Johnson is tearing it up on the wing for his club team, Borussia Moenchengladbach, right now:

How did M'Gladbach do in Bundesliga games Fabian Johnson played in 2015: 27 GP, 21W, 4D, 2L, 59 GF, 25 GA, +34 GD & 2-0 record vs Bayern M. — Brian Sciaretta (@BrianSciaretta) December 21, 2015

Correlation and causality are not complete strangers regarding the above stats.

3) Is something wrong at goalkeeper? This one hits at the core of everything it is to be a US fan -- we absolutely know we can rely upon the guy between the sticks, and have been able to breathe easy on that front since about 1988.

But both Tim Howard and Brad Guzan are struggling with their respective club teams right now, and there's no defined starter. It may be too soon to sound the alarm, but it's not too early to start considering that this spot isn't quite as strong as it has been in years past.

4) Deuce-less. Clint Dempsey started the year as the US captain. He was the one US player who came out of the Gold Cup unblemished, and when he was healthy, he was an elite player for club and country.

Yet he was stripped of the captaincy after a US Open Cup outburst, and spent most of his post-Gold Cup months injured. Once he regained his form, he was omitted from the team for November's qualifiers.

Another US legend noticed:

A point on the road in T&T is never easy. Can't help but wonder if it would have been 3 points with Dempsey playing tonight. #TRIvUSA — Landon Donovan (@landondonovan) November 18, 2015

Given the poor US finishing in that scoreless draw at Trinidad & Tobago, he's right to wonder.

And everybody is right to wonder if Dempsey will be back in 2016. He'll be 33 by the time the next pair of qualifiers come around, and you could argue that Wood, or Morris, or Jozy Altidore or the oft-injured Aron Johannsson "deserve" a look.

But the Yanks don't have a huge margin for error against Guatemala given recent form, and Dempsey has an undeniable track record. If he's healthy, omitting him would be a gamble.

The Best Defense

While I focused above on the ever-changing shape and make-up of the midfield, it's worth mentioning that the back line endured the same. Jones actually started as a sweeper in a 3-5-2 in last year's opener, and while that experiment wasn't replicated, it set the tone for a year of uncertainty.

Matt Besler started the year on the outside looking in, but eventually played his way back into what is maybe the first XI. Omar Gonzalez disappeared almost completely. Ventura Alvarado got a ton of early minutes, but was abused in the Gold Cup. John Brooks--along with Miazga--simply oozes potential, but as Panamanian forward Blas Perez showed, young defenders can and will make punishable mistakes.

The fullback spots are arguably even more of a mess, with Johnson moved up, DeAndre Yedlin used primarily on the wing, and DaMarcus Beasley pulled out of international retirement. Timmy Chandler has been bad when not hurt. Tim Ream has seen significant minutes at left back, but struggles shutting down 1-v-1 service, while Greg Garza has been repeatedly beaten for pace. Michael Orozco (!!!) got the start at right back against T&T last month, but he's a center back who was playing out of position, and offered no support in possession or on the overlap.

So it's not clear what's really going on back there, or what the future will bring.

And beyond anything else, that's probably the biggest concern in the US camp. Between 1988 to 2010, the US went from a laughingstock to a consistent, Top 20 team by relying upon small adjustments and incremental gains. What they lacked in individual flair they made up for with cohesion and chemistry, compactness in defense, and ruthlessness on the counter. The USMNT almost always knew who they were and what the plan was.

Right now, though, "change everything" seems to be the plan. In 20 games this past year, Klinsmann used 20 different lineups, and over the last two calendar years he's started the same XI in back-to-back games just once. It's hard for players to build on any promising performances in that situation.

And now, we sit back and see what changes come in 2016.