5. Great players do make great managers
The old saw that a top-level manager could never have played with distinction has been battered and discredited down the years but the four successful coaches this week all played for their countries and three had stellar international careers.
They are all young in terms of their profession, too. Pep Guardiola. 43, won 47 caps; Laurent Blanc, 48, won 97 caps; Diego Simeone, 43, played for Argentina on 106 occasions. Gerardo Martino, at 51, is the oldest and with one cap the least distinguished as a player yet is considered Newell's Old Boys' greatest. All four have taken a philosophy and successfully imposed it on a leading team. These sides bear the mark of their coaches in style and in execution.
4. Tata but not goodbye to Barcelona
Bayern Munich's 7-0 demolition of the Catalans in last year's competition was taken as the obituary for a great team.
The Barca of Guardiola was judged to have perished. Yet Tata Martino has taken the Catalan side to the top of La Liga and now has all but knocked out Manchester City in the Champions League. He has changed the Barca way with the odd long, diagonal ball interrupting spells of possession.
However, Barca remain Barca: clever on the ball - with Xavi and Iniesta still in control - and with Lionel Messi certain to improve dramatically as his fitness returns. They are still vulnerable in central defence but are improved and more resilient than the side which capitulated to Munich last season.
3. There is the top team. Then there are the top, top teams (copyright 'Arry Redknapp)
The Champions League is all about elitism. However, the gaps in quality are becoming discernible beyond the group level. Four sides won away from home in the round of 16, three of them with comfortable margins.
These results testify to the reality that money talks but they also suggest that a properly defined club strategy can pay dividends. PSG have gone for the quick fix with a massive cash injection and this has worked while Manchester City, with the same plan, must wait for a yield. Atletico Madrid (right), in contrast, have bought into the philosophy of a coach while wisely investing the returns of significant transfers.
There is now, unmistakably, an elite among the elite and the admission price to this club is substantial and beyond the means of most European leagues.
2. Buy what you need, not what you want
The forlorn sight of a willing and tireless Yaya Sanogo taking on the Bayern Munich defence at the Emirates was a damning indictment of Arsene Wenger's summer transfer policy. The absence of Olivier Giroud may have been blamed on a lack of form or a surfeit of contrition over the revelation he had spent a night in a hotel with a model who was not his wife.
Sanogo - at 21 and with 26 senior appearances - was the best replacement. Meanwhile, Mesut Oezil, the £42m signing from Real Madrid, missed a penalty and was involved in a row with Mathieu Flamini over the German's workrate, or perceived lack of it. The truth is that Wenger went into the transfer window in the summer determined to buy a striker. He emerged from it with a midfielder. That is not good management.
The elite are covered in all positions.
1. There may not be one-man teams but one man can make a team
Zlatan Ibrahimovic is a singular character. At Malmo as a boy, parents of other children drew up a petition to banish him from the team. He has fallen out with the best, most notably Pep Guardiola when both were at Barcelona.
The Swede has been dismissed as arrogant, overrated and inconsistent. Yet he is one of the great winners of the modern game. You sign Zlatan. Then you win the league. He has 10 championships from five countries, including six scudetti with three different sides. At international level, he has scored 48 goals in 96 games.
But he has never won the Champions League. He will be 33 this year. His increasingly determined attempts to win the trophy will be helped by the return of Edinson Cavani and by the quality that runs through the side.
Zlat the Brat is coming to the end of a bejewelled career. He may just become the story of an extraordinary Champions League campaign.