Xabi Alonso, the coach who ended Bayer Leverkusen's 150-year title drought in the Bundesliga, has bared his soul and mind in an open letter sharing his thoughts and reflections after a historic campaign.

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The Spanish coach and former footballer delves into the mentality of being one of the newest coaches in the football world. Alonso even mentions in the text that he questioned his reason for managing Leverkusen, especially after a heavy defeat to Frankfurt (5-1).

"I think there’s a moment when every young football coach stands on the sidelines, completely helpless, looks around the stadium, and asks, 'What am I doing here? How did I get here?' For me, that moment was my third game when Eintracht Frankfurt crushed us 5-1," Alonso begins his open letter published in The Players' Tribune.

Alonso recounts feeling that all the time invested and tactics devised were not good enough to lift Leverkusen. However, the Spanish strategist could not have imagined ending the season with both a Bundesliga title and a DfB Pokal trophy, finishing the campaign unbeaten.

"We were third from the bottom, and I don’t think anyone who saw that game would have predicted we’d win a title shortly after. We had lost the previous game 3-0 at home to Porto, and the team was struggling to recover. But I believed there was a lot of talent. So, before the Frankfurt game, I honestly thought, 'Hey, we can only get better.' As always, I worked hard to devise a good game plan. But once the game started, all my 'ideas' went out the window. All my research and notebooks full of tactics, all the hours of video I watched... the result never lies. Humiliating. I’m sure that after that result in Frankfurt, many people thought, 'Why did we hire this guy from Real Sociedad B?'" Xabi writes.

In his letter, Alonso highlights three key moments that led his team to start believing and eventually become champions: the first game against Leipzig, Jonas Hoffmann’s goal against Cologne, and their 3-0 victory over Bayern Munich.

"It all goes back to the 22-23 season. When we fought to draw against Atlético Madrid in the Europa League return match, I felt we had a special group. There was a look in the players' eyes: belief. If you’ve ever been a coach, then you know you can look into your players' eyes in the first two or three minutes of a game and know if it’s going to be a good day or a challenging day. There’s either belief or there isn’t. We had belief, even in defeat. At the end of that season, I asked many of our players with offers from other clubs to stay. I said, 'Please, trust me. If you come back, we’ll have a great season.' Some needed more convincing than others because it was a risk, let’s be honest. But in the end, everyone trusted me, and you see the results. From the first game against Leipzig this season, I knew we had the chance to compete for trophies," says the coach.

"That was our big test, mentally. If we gave in to the pressure of that moment, we would continue to hear the word 'Neverkusen.' We made a change in our system, and all the players embraced the idea. We wanted to control the game without the ball and wait for our moments to counterattack, which is not usually our approach, but it worked. At halftime, when we were up 1-0, the important thing was that I looked around the dressing room, and no one was interested in sitting back and defending the 1-0 lead. Everyone wanted to score more. There was no fear," he adds about his feat of defeating Bayern Munich.

In addition to recounting his season, Xabi Alonso concludes by assuring that the season was not perfect, as they lost the final against Atalanta. However, he notes that his goal now is to focus on the Champions League and defend the Bundesliga title.

"My journey to Leverkusen and my path to becoming a football coach is something I can only fully appreciate now that this incredible season has come to an end. Was it perfect? No, not perfect. We lost one game. I wish we could play it again. I really have to thank the club for entrusting me with this project. But most of all, I have to thank my players and staff for all their hard work. (And I hope everyone comes back because they know how much more we can achieve.) What’s next? A title defense. The Champions League. More history? With a bit of luck. More memories? Certainly. I’m happy that we never have to hear the word 'Neverkusen' again," Alonso concludes.

VIDEO | How Xabi Alonso Reacted to Leverkusen's First Defeat