Champions League: 10 Things We've Learned from This Year's Competition

With only three games left to go in this year's UEFA Champions League, it's a good time to reflect on the crazy ride that Europe's premier competition has taken us through this season.

As always, there have been some massive upsets and some incredible underdog stories. On the other hand, many of the world's best teams proved exactly why they're considered the best, while others left their fans massively disappointed by exiting Europe much earlier than expected.

In the coming slides, we'll take a look at all the major lessons learned from Day 1 of the Champions League up to the first leg of the Champions League semifinals.

I'll try to cover all the major stories and lessons learned, but if there's something that I leave out, do mention it in the comments section below.

Never Underestimate the Hearts of Champions

When APOEL managed to make the group stage of the UEFA Champions League in 2009-10, it was considered a major achievement for the team.

They'd beaten Partizan (of Serbia) and Copenhagen (of Denmark) to get to the group stages, and were deservedly applauded for recording three draws and three one-goal margin losses in a group consisting of Chelsea, Porto and Atletico Madrid.

But in 2011-12, APOEL completely defied expectations.

Once again, APOEL's run of three aggregate wins over six legs in the qualifying rounds was very impressive, but APOEL decided not to stop there this time around.

Placed in a group without a world heavyweight, APOEL recorded two massive 2-1 victories over Zenit St. Petersburg and Porto, and their three additional draws gave them a total of nine points, enough to top their group.

The magic didn't stop there, as APOEL's determined players secured another against-all-odds victory over Lyon in the Round of 16, beating the French giants on penalty kicks.

In the quarterfinals, the gulf in class between Real Madrid and APOEL was too big to be overcome by sheer grit and determination, but APOEL had already outdone themselves by that point.

They'd secured improbable victory after improbable victory, and assured their place in Champions League folklore. There were many great underdog stories in this year's Champions League, but none are as good as APOEL's.

A Lot Changes in the Span of a Year

When Villarreal qualified for the Champions League last season by finish four points ahead of Athletic Bilbao, Atletico Madrid and Sevilla, they looked like a club in great health.

But by late October, they'd gone from a club in great health to a club on the brink of disaster. How did the team's fortunes change for the worse so drastically?

It started with the sale of Santi Cazorla, arguably Villarreal's most creative player at the time, for €19 million to Malaga. The argument was made that Villarreal needed the money, and indeed they did, but the sale represented a major loss of talent for the Valencian club.

With the the money earned from Cazorla's sale, Villarreal brought in Cristian Zapata from Udinese and Julian de Guzman from Mallorca. While the former gave Villarreal's defense a major boost in quality, the latter proved unable to replicate the form he showed with Mallorca the season before.

The situation became so dire that Marcos Senna, the team's 35-year-old veteran who looked to be on his way out at the end of the 2010-11 season, was recalled to the starting lineup as one of the few alternatives to De Guzman.

Of course, the straw that broke the camel's back was Giuseppe Rossi's cruciate ligament in late October. Villarreal had been struggling to that point, but without the striker who put away 32 goals for the Yellow Submarine last season, they were in absolute shambles.

They lost their remaining three Champions League games without hardly putting up a fight, and to this day sit only five points above the relegation zone.

What a difference a year can make.

The Champions League Can Be Awfully Cruel

Very few football fans pay attention to the Champions League before the group stage of the competition. However, it's important to give some recognition to the guys who just missed out.

Consider Maccabi Haifa. After securing aggregate victories in the second and third qualifying rounds of the Champions League, Haifa were eliminated in the cruelest of ways as they lost to Belgium's Genk on penalties.

Malmo and Wisla Krakow deserve shout-outs too for missing out by a single goal in the play-off round after surviving the second and third qualifying rounds.

Last but most certainly not least, Udinese deserve recognition—and probably some pity too—for how their Champions League journey was halted prematurely.

After an impressive Serie A campaign in 2010-11, Udinese secured the fourth spot in Serie A and entry into the Champions League via the play-off round. They'd beaten off competition for fourth place by finishing above Lazio on goal difference and above Roma by three points.

Although Udinese had seen a massive exodus of talent in the summer of 2011, they still had enough firepower in the team to be considered a fearsome force. Had they faced a team other than Arsenal or Bayern Munich, and maybe Benfica, they would've likely won.

But they were pitted against Arsenal, to their manager's displeasure. Despite being the underdogs though, Udinese came very close to winning the tie.

They put heavy pressure on Arsenal's goal in the first game but were unable to find a breakthrough, and in Italy Antonio Di Natale nearly put Udinese 2-1 up but had his penalty impressively saved by Wojciech Szczesny, before Theo Walcott put the game out of reach.

Unfortunately for Udinese and the other teams who just barely missed out on the Champions League group stages, the Champions League doesn't offer conciliatory prizes for those who fail to make it to the big stage of the competition.

These teams cruelly missed out on the prestige and the major economic boost provided by making it to the group stage of Europe's premier competition.

Experience Is Huge in the Champions League

The 2011-12 Champions League was not kind to many of its newcomers.

Manchester City entered the Champions League as one of the favorites to contend for the title in May, but a loss to Bayern Munich and a loss and draw vs. Napoli ended that dream in the group stage for the Citizens.

Similarly, Lille, last year's French champions, struggled more than France's more experienced teams, Lyon and Marseille. Trabzonspor failed to build on their momentum from last year, and Genk's inexperience also showed as they were unable to register a single win.

Borussia Dortmund's fourth place finish in Group F was especially upsetting, since most pundits had them as either the first or second strongest team of the group.

On the other hand, many Champions League veterans did well despite their poor domestic campaigns.

Despite their awful start to the EPL season, Arsenal managed to finish 1st in Group F, as did Inter, who currently sit 7th in Serie A, and were lower than even that at the start of the season.

Marseille and Lyon have both had pretty awful Ligue 1 seasons by their standards, yet both qualified for the Champions League knockout rounds as well.

...But It's Not the Only Thing That Matters

Of course, there were many experienced teams who just couldn't cut it in the Champions League this season.

Although Manchester United's resilient grit has kept them pushing for another title in the English Premier League, their lack of creativity in midfield cost them in the Champions League.

No wins in four games against Benfica and Basel meant that they found themselves dumped out of the group stage for the first time since the 2005-06 season.

Porto also endured a poor campaign which saw them finish third in a group they were heavily favored to win. Despite breaking all kinds of records under Andre Villas-Boas last season, this year they were a big disappointment on the European stage.

The Margin Between Success and Failure Is Very Small

We've already talked about the teams that just barely missed out on the group stage. Now we can talk about the teams that just barely missed out on the knockout rounds.

Going into the final round of games, many teams still had a good shot of making the knockout rounds.

Manchester City had lost their must-win game against Napoli in Matchday 5, but if they won on Matchday 6, and Napoli lost or drew to Villarreal, they would've qualified for the knockout stages.

As it happened, City did beat Bayern Munich, but Napoli overcame Villarreal to keep the second place spot.

Manchester United were also were in pole position to qualify for the knockout rounds on Matchday 6, although their elimination was much more disappointing than City's as their fate was actually in their hands.

In Group B, second through fourth still had a chance of qualifying on the final day, and the same was true of Group F (technically at least).

And of course, Marseille's dramatic 87th minute goal and Lyon's 7-1 win over Dinamo Zagreb brought both team's fans joy in an otherwise very disappointing season.

At the end of the final gameday of the final round of the Champions League group stage, the teams that got the results they needed progressed.

However, had the results differed ever so slightly, we could've seen City or United, or both, make it the Champions League knockout rounds.

...But Not for Everyone

Real Madrid and Barcelona looked significantly more impressive in the Champions League group stages than the rest of the teams in the group stages.

They finished with 18 and 16 points respectively, seven and five points more than the average number of points it took to qualify for the knockout rounds this season (11).

But Real and Barca weren't the only two teams whose impressive group stage performances stood out. Bayern Munich also handled the group stages well, recording four wins and one draw after five games in this year's "Group of Death."

Their 2-0 loss to Manchester City on Matchday 6 took some gloss of their impressive group stage campaign, but they still deserve recognition for the superior quality they showed.

It's no surprise that these three teams are still considered the three favorites to lift the Champions League trophy this May, with Chelsea a rather distant fourth.

Consistency Is the Key to Champions League Success

In the 2009-10 Champions League, Lyon made it all the way to the Champions League semi-finals, beating Real Madrid and Bordeaux (who'd finished with a 5-1-0 record in the group stages that season), before being beaten 4-0 on aggregate by Bayern Munich.

In the 2010-11 Champions League, Schalke impressively beat Valencia and Internazionale on their way to the semi-finals, before receiving a tough reality check in the form of a 1-6 loss to Manchester United on aggregate.

What did these two teams have in common? They experienced success at varying stages of the competition, but could not maintain that throughout.

In 2009-10, Lyon picked up 13 impressive points in the group stage, and even put on admirable performances vs Real Madrid in the Round of 16. But they fizzled out in the quarterfinals, progressing to the semis only due to a 3-0 lead they'd built up in the first leg of their matchup with Bordeaux.

Similarly, Schalke played well in the group stage, and recorded impressive victories against Valencia and Inter Milan, but poor domestic form eventually spilled over into their European games as they were torn apart by Manchester United.

And this year, although we haven't yet completed the semi-final stage of the Champions League yet, AC Milan followed the lead of Schalke and Lyon.

They looked like genuine contenders in the group stage, recording two very credible results against Barcelona (a 2-2 draw and 2-3 loss), and shocked Europe with an emphatic 4-0 victory over Arsenal at the San Siro in the Round of 16.

But they failed to demonstrate consistency in the second leg, coming very close to allowing Arsenal to score four unanswered goals at the Emirates. Unfortunately for Arsenal, Christian Abbiati's heroics made sure that Arsenal's goalscoring was halted just one goal short of the needed total.

But the damage had been done. Though many would argue that AC Milan were robbed by the referee's awarding of a second unfair penalty in the second leg of the AC Milan-Barcelona matchup, one has to admit that AC Milan's offense was toothless over both legs.

Aside from Antonio Nocerino's goal, AC Milan struggled to hold onto possession or create enough scoring opportunities to keep up with Barcelona. 

Furthermore, the defense that looked resolute and impenetrable at the San Siro, was much more fragile and accessible at the Camp Nou.

Chelsea may have ridden their luck to get this far in the Champions League, but if his history is anything to go by, they'll most likely lose the tie vs Barcelona at the Camp Nou. Historically, it's the consistent teams who prosper in the Champions League.

All Good Fairytales Must Come to an End

This year, Champions League watchers were treated to two feel-good underdog teams in FC Basel and APOEL. Both teams far surpassed the expectations anyone had set for them at the start of the year.

But as is the case with all underdog stories in the Champions League, both FC Basel and APOEL eventually were exposed by the real contenders for the CL trophy.

After going up 1-0 vs Bayern, Basel were destroyed in Germany, with Bayern Munich producing seven goals against the overachievers from Switzerland.

As for APOEL, they endured an 8-2 defeat from Real Madrid, though the scoreline does not do justice to the hard defensive work they put in for much of the first leg in Cyprus.

To an extent though, Chelsea's run in the Champions League is very much a fairy-tale run in of itself. Sure, Chelsea have many experienced heads who've tasted domestic success, but almost no one had them beating Napoli once they lost 3-1 in Italy.

We'll see how long that run lasts, but as I've already said, numerous factors, history being one of them, point to Barca emerging victorious at home.

In the Final Stages, Mistakes Get Punished

When Barcelona took on Chelsea this past Wednesday, they put in a nearly flawless performance. They dominated possession, took way more shots, and on another day, they could've put five goals past Petr Cech.

But they made one mistake—conceding possession to Frank Lampard in the center of midfield—and that mistake was quickly punished, as Ramires got the ball to Didier Drogba to convert Chelsea's only shot of the game.

Think back to Bayern's matchup with Real Madrid. Both teams played well and had good scoring chances, but ultimately, Bayern won for their ability to capitalize on mistakes.

Ribery scored off a corner due to a poor defensive clearance from Sergio Ramos, and Mario Gomez was able to convert Philipp Lahm's cross because Fabio Coentrao did an awful job of defending him.

All this just goes to show one thing—that in the semi-finals, when you're playing the best teams in world football, mistakes will get punished.

It's something to keep in mind as we gear up for the second leg of the Champions League semi-finals.

We can use history and numbers and analysis to determine who is most likely to emerge victorious, but in the end, it all comes down to this: Whoever makes fewer mistakes will win, and whoever makes more mistakes will lose.

It may sound ridiculously simple, but it's the truth. If Chelsea or Bayern Munich turn in performances as strong and error-free as they did in the first leg, they'll both progress, but if they let Madrid and Barca's pressure get to them, they will likely find themselves exiting the competition before the final round.