The group stages are over, and from here on in, things get serious.

The European Championships have always been less predictable than the World Cup, with far more upsets and unfancied winners.

Historical triumphs from Greece, Denmark and Czechoslovakia have shown that the field is far more open than many international competitions, and never more than in 2016.

What have we learned from the group matches, and what should we look out for in the knockout rounds?

When UEFA announced that it was to increase the number of teams at Euro 2016 from 16 to 24, the general consensus was that this was A Bad Idea.

The Football Associations of both Germany and England spoke out against Michel Platini's expansion, Joachim Loew suggested that the old format "made for great matches from day one", while Henry Winter wrote in the Telegraph that "international football should be kept elitist".

The Group Stages of the tournament have made a mockery of such sentiment. Teams that were meant to be there simply to make up the numbers have surprised or excelled, and the carrot of qualification places for four third-placed teams has meant we've had drama to the very end.

Three of the six group winners come from teams outside of the elite of FIFA World Rankings. Hungary (20th), Wales (26th) and Croatia (27th) topped groups ahead of some of the more favoured sides. Iceland (34th) and Northern Ireland (25th) may have been seen as cameo acts in this tournament, but both have shown themselves more than capable of holding their own.

Two of the four sides that qualified via the playoffs - Hungary and Ireland - are still in the competition. Which countries are the top scorers in the tournament? Spotters' badges if you said Wales and Hungary. Both have six. What price Gordon Strachan's thoughts on 32 teams next time?

We may not have proof of the success of the "wild card" for third placed teams in terms of the competitiveness of the second round, but there can be no doubt that it has added significant drama to proceedings. Anyone who watched the final-day permutations in Groups E and F will testify to that.

This is the kind of sweeping statement that tends to immediately come back to haunt analysis, but the standard of refereeing has largely been excellent. There may be the standard complains about pulling shirt-pulling and "Italian defending" (surely as evocative a football phrase as "the Makelele role"?), the officials haven't been making headlines.

Matches have been allowed to flow, officials have been sympathetic, and referees have generally been custodians of matches, rather than regulators of them. When the failure to spot a goalkeeper in his six yard box for a penalty is one of the major talking points, you know pundits are having to look hard for controversy.

In Euro 2012 there were 3.96 yellow cards per game after the group stages. This year there have been 3.58 yellow cards per game, a fairly significant drop off.

One of the main features of Euro 2016 has been the significant number of late goals scored in the tournament. We do need to temper this excitement slightly, by pointing out that this tends to happen in tournament football, and it's not been especially uncommon in recent years, but there are still some oddities.

A total of 69 goals have been scored in France, and while that is the lowest average goals per game since 1992, there have been far more in the final ten minutes. 29% of all strikes at the championships have come after the 80th minute, a total of 20 goals. By way of comparison, just 24 goals have come in the entire first 45 minutes.

Why so? Of course, the expanded tournament, and the fact we've seen relatively few one-sided encounters, which in turn has meant teams have it all to play for right until the very last minute.

Equally, we've seen an increased importance in the squad game and substitutions. Seven of the goals scored after the 80th minute have been from players coming off the bench.

It is obvious that having great full backs provides a huge advantage to a team, what is perhaps less obvious is how weakened sides are without them.

While Spain's recent successes have always been put down to their possession football, their full backs have always given them width their philosophy doesn't immediately prioritise. Germany have a variety of goal threats, but were able to utilise Philip Lahm as an attacking threat, a defensive organiser, and a viable out ball to keep possession.

Some of the favourites at Euro 2016 have obvious deficiencies in this area. France have good options up front, a dynamic midfield, and an exceptional goalkeeper, but they are still relying on Patrice Evra and Bacary Sagna at full-back. Germany's strikerless front line have struggled to get behind teams, in part because they haven't always had reinforcements from wide areas.

Arguably the most surprising example are Belgium. The most expensive squad at the Euros have quality in almost every department, and almost every member of their squad has experience of winning at the very highest level. However, they are seriously lacking at the back. Jan Vertongen is usually shoehorned in at left-back, with the inexperienced Thomas Meunier on the right.

Their depth of attacking prowess is enough to see off most sides, but against the stronger opponents - as we saw against Italy - they struggle to find a Plan B, and are reduced to narrow, repetitive patterns.

Italy have been one of the most impressive sides, thanks in no small part to their width. Emanuele Giaccherini may not be the traditional full-back, but he has been hugely effective when deployed as a wing-back, scoring once and assisting another of the Italian goals. Such width may be key in the second round against Spain, who struggled to deal with an equally wide Croatian threat.