1.ARSENAl
As Tuesday night's dismal loss at Swansea so painfully underlined, Arsenal still have major issues to address in defence, and particularly in between the posts. Indeed, it is worth noting that no goalkeeper across Europe's Big Five leagues has made more mistakes leading to goals (4) than Petr Cech.
However, the January transfer window has gone better than even the most optimistic Arsenal fan could have envisaged.
The Gunners began the month faced with the prospect of losing their two best players, Alexis Sanchez and Mesut Ozil, on free transfers this summer.
Sanchez has since defected to Manchester United but that is a positive given how negative an influence he had become on the Arsenal dressing room.
Furthermore, the Gunners have acquired a potentially excellent player in return, Henrikh Mkhitaryan, who should flourish under a coach who affords his attackers greater freedom, particularly as he will be playing alongside his old pal from Borussia Dortmund, Pierre-Emerick Aubameyang.
Ozil's surprising but most welcome decision to extend his contract was also clearly influenced by the appetising prospect of providing passes for the Thierry Henry-like Gabon striker.
Of course, the £56 million paid to BVB for Aubameyang’s services constitutes a club-record fee for the Gunners but when one considers that it was partly funded by the removal of some bench-warmers (Theo Walcott and Francis Coquelin, for a combined £37m), then it is impossible to view Arsene Wenger's winter window wheeling and dealing as anything other than a success.
Will Arsenal finish in the top four? That remains to be seen. But have they now a better chance of doing so? Absolutely.
2.MAN UTD
Given the way in which Jose Mourinho embraces excuses and fabricates facts, it's rare to find oneself in agreement with the master manipulator of the media.
However, the Manchester United boss had a point when he claimed that exchanging the unwanted Mkhitaryan for the in-demand Alexis Sanchez was a masterstroke.
"He was cheap, wasn't he?" Mourinho enthused. "Free transfer! He was free. So, for that price, he's fantastic.
"I think everybody thinks the same. Everyone has to agree that he is a fantastic player and the team that got him has a plus."
No arguments here. Whether he is good enough to shine in spite of Mourinho's trademark pragmatism against the very best sides is open to debate – certainly, the early signs against Spurs were not encouraging – but there is no denying that Alexis is a world-class player.
In addition, the fact that the versatile Chilean attacker was all set to join Mourinho's nemesis, Pep Guardiola, at Manchester City before United hijacked the transfer only made this particular "orange" taste all the sweeter for the preening Portuguese.
3.BARCELLONA
It was only last August that Barcelona defender Gerard Pique mournfully admitted, "In the nine years that I have been here, this is the first time that I feel inferior to Madrid."
Luckily for the proud Catalan, that depressing sensation did not last long. During the first half of the season, the Blaugrana reasserted themselves as the best team in La Liga, even routing a ragged Real side at the Santiago Bernabeu just before Christmas.
Consequently, if anyone needed a big signing this month, it was los Blancos - and yet whereas there wasn't a single new arrival in the Spanish capital in January, Barcelona have been the winter window's biggest spenders.
The Blaugrana spent a combined total of €131.8m on Philippe Coutinho and Yerry Mina, boosting Ernesto Valverde's hopes of emulating predecessors Pep Guardiola and Luis Enrique by winning a treble in his first season in charge.
The aerially-dominant, all-dancing centre-half Mina should prove an absolute steal at €11.8m and while Coutinho's mid-season arrival for a whopping €120m (which could rise to €160m depending on add-ons) is peculiarly timed, particularly as the Brazilian is cup-tied in the Champions League, runaway Liga leaders Barca are now in a position to rest the likes of Andres Iniesta on a regular basis.
In addition, Barca have managed to remove a couple of high earners from their wage bill, Javier Mascherano and Arda Turan, while at the same time sending Rafinha and Gerard Deulofeu out on loan.
Madrid, by complete contrast, are now preparing for a must-win Champions League last-16 showdown with Paris Saint-Germain with the same core of group of players that have looked so jaded in recent months.
In short, Pique is feeling superior again...
“Liverpool is not a club that has to sell players," manager Jurgen Klopp declared last summer, after Barcelona upped their bid for Coutinho. "That is set in stone, so what they offer in the end doesn't matter.”
Why, then, did Liverpool agree to sell the Brazilian to the Blaugrana in January, at a time when the Reds are locked in a battle with Manchester United, Chelsea, Tottenham and arguably Arsenal for three of the Premier League's remaining top-four berths, as well as looking forward to a winnable Champions League last-16 tie with Porto?
The money on offer (€120m, and a potential €40m in add-ons) was colossal, particularly when one considers Coutinho could hardly be considered one of the top five players in the world, but would the fee have been much lower at the end of the season?
Furthermore, while Coutinho clearly wanted to leave, would he have downed tools and refused to play in this, a World Cup year? He submitted a transfer request last summer yet still contributed 12 goals and nine assists during the first half of the 2017-18 campaign – would he really have gone on strike again had he been told his dream move to Barca would only be allowed to go through this summer?
Of course, Liverpool's frustration at losing Coutinho has been offset by the belated arrival of Virgil van Dijk from Southampton, and the Dutch defender should undoubtedly strengthen the Merseysiders' brittle back four.
However, when it comes to evaluating a team's transfer window, one must ask oneself if the squad is stronger or weaker than it was at the beginning of the month?
Liverpool are weaker. They were dealt all the aces but ended up splitting the pot.
The centre of defence has been improved but it remains reliant on two of the worst goalkeepers in the Premier League. Indeed, Lorius Karius has now been promoted to first-choice, a staggering decision given that he has the worst save percentage (44.44) of any goalkeeper to have played at least five games across all of Europe's Big Five leagues.
Given Roma were clearly desperate for money in January, Liverpool really should have pushed to sign their current No.1, the excellent Alisson.
Furthermore, Daniel Sturridge's loan move to West Bromwich Albion means that Liverpool are an injury to Roberto Firmino away from having to turn to Danny Ings or Dominic Solanke - no goals this season - to lead an attack now shorn of the versatile Coutinho.
The pressure on Mohamed Salah, Firmino and Sadio Mane to continue carrying this top-heavy team through the remainder of the season has just got a whole lot heavier.