How do we decide who is the best at any one position?
First of all, labeling someone the best is not conclusive or permanent. A ranking of players by position will change every season—multiple times throughout—as injuries, form, team chemistry and various other factors influence such a list. It is really impossible to have a unanimous view on such a ranking. Everyone has their own opinions about what the most important strengths and weaknesses are by position.
More importantly, those strengths are measured not according to a universal standard, but by the level of success achieved in a given team or system. One player's best attributes may be utilized perfectly at one team, but make them far less valuable at another.
So in a sense, any ranking that declares one player as the best at their position is not only inherently flawed, but fickle.
With that pretense set, I am here to provide a list of the top 15 left backs in Europe.
While the players are ranked in order from 15 to 1, the order is certainly up for debate. In fact, discussion and disagreement is encouraged.
Please note that while players are ranked, the gap between positions is not that great. The consistent and current ability shown by someone in the top 3 is not tremendously better than a player just outside of that level.
Without any further ado, here are the top 15 left-backs in football.
Club: Rubin Kazan
This tough tackling fullback continues to fly under the radar because he plays in Russia. The versatile defender can play on either flank, but has the discipline, timing and balance of a central defender with the attacking prowess of a wing-back.
He has tremendous acceleration and speed. He is also one of the better tacklers on this list and cuts off a lot of passes.
The former Porto star was allegedly a target of Chelsea over the last couple of summers, but ended up in Milan instead where he now plays as a left midfielder with Inter.
There is a reason the Blues were aiming to replace their club legend Ashley Cole with the Uruguayan.
He may start at midfield, but actually ends up often switching duties during matches. Having such a defensively sound midfielder roaming centrally with Yuto Nagatomo on the left makes Inter’s flank very difficult to penetrate.
Pereirra is a very intelligent, balanced defender who rarely gets caught out of position, but still contributes greatly in attack.
Azzurri fans should show plenty of gratitude to this fullback. He played a huge role in Italy's run to the final of the 2012 Euros.
After Christian Maggio and Ignazio Abate were forced out of the semifinal match against Germany, the former Palermo defender was asked to slot into the right back position with Italy moving from the preferred three-man defense to a more traditional 4-4-2.
Despite playing in a unnatural position, Balzarretti played excellently and helped upset the mighty Germans to book a date against the reigning champions Spain.
The Italian then finalized a deal with Roma that saw him move to the Italian capital where he has continued to be one of Serie A's best left backs.
Perhaps the best way to describe Nagatomo is as a workhouse.
The Japanese star is the most versatile, interchangeable player on this list. He can play on either flank as part of a four-man back line, on either side of the midfield, and even on the wings of a three-man line.
The Inter man has incredible stamina, unbelievable pace, and tremendous positioning. He earns a lot of fans for his incredible work-rate as he plays both sides of the pitch relentlessly for 90 minutes every week.
Nagatomo is the kind of player that almost any fan can enjoy watching.
Club: Manchester United
Evra is not the same player he once was, but he is still one of Europe's top fullbacks, even at 31 years of age.
The Frenchman has caused the Manchester United faithful to lose confidence in him over the last 18 months due to inconsistent play, more frequent lapses on defense and a general decline in ability, but the left back was one of the most dominant players of his era. Many people are a bit too critical of the left back in part because of the unbelievably high standards he set for himself over the last half decade.
Evra has certainly digressed and proves a liability with his all-too-frequent lapses, but he is still one of the top defenders in the Premier League.
He is athletic, defensively sound and remains a danger in attack. Despite being notably less dangerous going forward than in times past, Evra is still creative and pacey enough to contribute.
Club: Manchester City
Oh how Arsenal would love to have this one back—as is unfortunately the case with many players these days.
The Frenchman had already been one of the top left backs in England when he played for the Gunners and is now entering that next level. It is not crazy to imagine the polarizing star becoming the best in the league within a few years.
He has great vision which allows him to be one of the most accurate defensive passers in England and averages roughly four interceptions per game—very good for a fullback.
Clichy has tremendous quickness on and off the ball and has now become far more consistent than he ever was under Arsene Wenger.
Malaga's Nacho Monreal is a very underrated star who is currently a key member of one of Europe's top defenses.
The Spaniard does not have the speed of Jordi Alba, but he is a better defender and is not considerably weaker in attack.
Monreal He has good speed to cover his teammates and rarely gets caught too far forward—unlike Jordi Alba who still too often finds himself too far in the opposing half.
He is a superb defender and has been the second-best left-back in Spain over the last season and a half.
Malaga are currently in a load of financial trouble and have lost a few key players, but few losses would be greater felt than that of Monreal.
If you were watching Everton play for the first time, it would be easy to confuse Leighton Baines for a winger given his style of play and the strengths he possesses as a fullback. The English fullback looks more comfortable in the opposing half, where he sets up a lot of goals and takes plenty of great free kicks.
He is a solid tackler, but is still just an above average defender. Who knows how many caps he'd have by now if not for Ashley Cole
There is a reason Manchester United was allegedly so keen on signing him this past summer after being named to the PFA Team of the Year last season.
If this list were combing potential with the current level of success and talent shown, Alba would be fighting for a top three spot. As it is however, he is still one of the ten best left backs in the game.
The former La Masia product made his way back home this summer when he signed for Barcelona just before the Euros started. It turned out to be bad timing for his former club Valencia as a superb performance only increased his value.
Alba was Spain's most consistent and best defender at the tournament and showed signs of being a world class player.
He is not quite at that level yet, but the 23-year-old looks like he will soon be one of Europe's elite defenders.
Club: Zenit St. Petersburg
Zenit's left back is one of the more underrated defenders in Europe. Unfortunately, he missed out on a chance to play in this summer's Euros which would surely have helped his reputation abroad.
His being under investigation for match fixing prevented him from being called up for Italy even though he was later cleared of any charges. Criscito is sure to regain his spot on the national team soon as he is one of the top defenders on the continent.
The Italian is one of the major reasons Zenit have been so dominant in the Russian Premier League over the last 18 months and he will get a chance to prove it in the Champions League this year.
Club: Real Madrid
Oh how lucky Jose Mourinho is. He is the only manager in football with two left backs who could be counted among the top five in football.
The Portuguese star gives Real Madrid a bit more defensive solidity that they sometimes lack with Marcelo on the pitch and also adds to the attack a bit.
For some reason, Coentrao plays much better for his national side than he does in the Spanish capital, but he is still a top class fullback at the club level. More consistent playing time would likely remedy many short-comings.
For his national side—and at Benfica before it—Coentrao has proven to be as deadly in attack as he is defensively.
He makes the case for being perhaps the best left back in football, but just can't seem to replicate that balance in Spain.
He is a better defender than Marcelo, as good a passer, and almost equal in attack when at his best. Of course, he is rarely at his best.
Club: Real Madrid
He has character issues and is still not as defensively sound as his Portuguese counterpart, but Marcelo is the perfect representation of the modern fullback.
In today's football, teams scout left backs differently. They target players with speed, great feet, good link-up play with their forwards and good attackers. In short—wing backs.
Marcelo encapsulates all of these things. He is arguably the most exciting player on this list given his rare mix of technical ability, incredible dribbling skills and fantastic ability to make quick, space-creating passes.
The Brazilian forms one of Europe's best fullback-to-forward combos with Cristiano Ronaldo which makes Real Madrid's left flank almost impossible to control.
But as much as he has improved, Marcelo does still have frequent lapses on the defensive end. He relies to much on his speed, to the point where he ventures too far forward in hopes that he can make up any positional mistakes by racing back to cover his line.
If Marcelo can learn to have more discipline, he could become Europe's best left back in due time.
Club: Atletico Madrid
Luis proved last season that, when fully fit, he is one of Europe's best fullbacks. He was the best left back in La Liga last season.
Considering that three La Liga stars are in the top five on this list and guys like Nacho Monreal are also in contention, being the best in Spain speaks volumes about the South American.
He is far better defensively than the likes of Marcelo, Jordi Alba and Premier League star Leighton Baines. He is not exactly weak in attack either: just ask Chelsea fans.
If not for his horrific injury back in 2010, it is likely that the Atletico man would be starting for Brazil rather than Marcelo. As is typical in Spain due to the incredible gap at the top of the table, playing for a team outside of the big two causes Luis to be incredibly underrated.
If the Brazilian moved to Manchester United next season to replace Evra, he'd be on almost any top 10 list. For now, he'll have to settle for just this one.
He is one of the most balanced, complete players on this list and should not be as overlooked by fans as he is.
Cole did not have as spectacular a season overall last year as he would have liked, but played his best football when it mattered most.
The fullback was an absolute rock in the Champions League last spring. In Chelsea's final three matches of their title run, Cole shut down some of the best and most dangerous wide men in football.
He kept the likes of Alexis Sanchez and Robben quiet and uncomfortable and helped the front lines of Barcelona and Bayern to play a game they were less comfortable with. He made the former take risks from areas they were less comfortable with and managed to block countless shots in the tie.
At his best, Cole is a level above almost every other left back in football.
While at least one rather serious fault can be found in almost every other player on this list, the same is harder to argue for the former Arsenal star. He is a great passer, incredibly disciplined, can read and shut down almost any attack, and is a sound tackler.
Looking at the past decade of European football, Ashley Cole is probably the only Englishman who would make a World Starting XI.
He may not be at his absolute best anymore, but he is still the best left-back in football.
Club: Bayern Munich
Yes, I know he primarily plays as a right back now, but the German captain is just that good. Being the best and most complete right-back in football, Lahm is the only player who can boast at being top 3 at both flanks.
He played left back for years at Bayern and Stuttgart and still gets the occasional start out left for the national team—such as at this summer's Euros.
Lahm is probably the best passer on this list, is very intelligent and times his runs perfectly, and has virtually no weaknesses.
Contentious pick? Sure. But an unfair one? Absolutely not. There is no better full-back alive than Germany and Bayern Munich's Philipp Lahm.