La Liga has gone through tectonic changes this summer. One of the best players of all time, Lionel Messi, could not continue at Barcelona due to financial issues the club is experiencing, and thus the Spanish top-flight lost a huge part of its draw. However, this does not mean that other teams were not active as well. Here are the three best La Liga signings of the summer transfer window:

David Alaba – Bayern Munich to Real Madrid, free

It is difficult not to start with David Alaba, as the Austrian came in perfectly for a bleeding Madrid defense. After losing Sergio Ramos and Raphael Varane in the same window, Los Merengues needed to strengthen their defense and the former Munich left-back was a great signing. Even at the start of this season, it was clearly shown that Alaba will be a fine addition, as he was absolutely pacing on the left flank and exchanging quick passes with Karim Benzema and Eden Hazard, something the usual left-back of Madrid, Ferland Mendy, has somewhat struggled to do in the past.

However, Alaba was not brought in simply because he is a world-class left-back – as it is clear that the aim was always for Mendy, Marcelo, and youngster Miguel Gutierrez to share minutes in that position for the La Liga giants. Alaba was brought in to cover multiple positions, most likely to cover for Nacho Fernandez and Eder Militao in the middle, and for Casemiro in the holding midfielder role. Alaba spent his last few seasons in Bayern playing mostly center-back, while he is routinely put in the middle of the park for the Austrian national team.

While Madrid certainly did not have the summer they expected, losing their beloved manager Zinedine Zidane and two stalwarts in Ramos and Varane, signings of Alaba and Eduardo Camavinga certainly saved some face for president Florentino Perez. Perez is widely expected to try and attract many big-name players in the next window, with the names Kylian Mbappe and Paul Pogba gathering the most attention.

Memphis Depay, Lyon to Barcelona, free

While Madrid did have a turbulent summer, it would be a severe understatement to say the same about their La Liga rivals. After tough campaigns in the last two Champions Leagues and poor performances in the league adding to that, Barca underwent major changes this summer. Of course, after 20 years in the Catalan club, the Argentinian wizard Lionel Messi was forced to leave the club caused by the previous irresponsibility with various transfers and contracts. Messi is not someone that can be easily replaced, as the new PSG man routinely scored when Barca needed it most, but it can still be said that in the position they were, Catalans made one great deal.

Memphis Depay might still remain in a lot of fans' minds due to the major failure he was at Manchester United, where he was brought on to continue the legacy of the number 7 shirt, somewhat tainted by Angel Di Maria. However, his goal-scoring record in Lyon cannot be overlooked, as he routinely scored for the French giants. His best season was the ultimate one in Lyon, scoring 22 goals in 40 appearances, including 20 goals in the league. Considering the fact that Barcelona just lost 30+ goals per season, having someone like Depay will pay dividends right away.

Also, in terms of the footballing aspect, Depay can play multiple positions and, if needed, move to the side or in the center of the attack. He is a prolific finisher, but also very pacey and can attack defenses with lightning-fast runs in behind the last line of opposition players. His strength should not be underestimated as well, regardless of his relatively small frame. It will be interesting to see how Barcelona will get on this year in general, as it is widely believed that this squad is simply here to transition from one to, for the fans hopefully, another Messi-like figure. That, however, does not mean that Depay and the Catalans will not be a threat to any opposition in La Liga or Europe.

Rodrigo De Paul, Udinese to Atletico Madrid, $41.5 million

A bit of a change from the past two transfers, as there was money exchanged in this deal, the La Liga champions further reinforced their midfield with the Argentinian from Udinese. De Paul will be joining his compatriot coach Diego Simeone and it is widely expected that he will need to fill the gap left by Saul Niguez, who was sent on loan to Chelsea. Regardless of the Saul departure, Atletico Madrid has assembled a very impressive midfield, especially with the signing of the central midfielder from Italy. Other than De Paul, there are club veterans Koke, Thomas Lemar and Yannick Carrasco, and, arguably, the best player in Atletico Madrid's midfield last season, Marcos Llorente.

However, coming back to De Paul, he should be able to fulfill tasks that were not completely accepted by Saul, who was routinely asked to play on the flanks and be more involved in creating the attack for the Los Colchoneros. De Paul is great at completely controlling the midfield, a skill he was not able to fully express in Udinese, which was a mid-tier club. Now, joining the champion of a major league with elite players around him, De Paul should be flourishing and it seems like Atletico will be able to handle midfields of Real Madrid and Barcelona. In the past, it was the defense and tactical settings implemented by Cholo Simeone that were difference-makers for Atleti, but now they have a very potent La Liga midfield to boast as well.

Combining the De Paul transfer with the return of Antoine Griezmann, it definitely seems like Atletico are very serious about repeating their feat from last year and winning the title in Spain again.

Spanish clubs were incredibly active in this window, as Barcelona was trying their best to find suitable players for their financial situation, Atleti trying to further improve and Madrid doing its best to get its hands on Mbappe. However, even the smaller La Liga clubs made some worthy moves, and while there was no space on the list, it is still important to mention Javier Pastore joining Elche on a free transfer from Roma and Mallorca snapping up the supremely talented Matthew Hoppe from the struggling Schalke. It will definitely be a very interesting season in Spain.