London: Legendary Netherlands defender Ronald Koeman has lashed out at former English Premier League (EPL) champions Manchester United for their treatment of recently sacked manager Louis van Gaal. United announced van Gaal's removal as manager in the immediate aftermath of their FA Cup final victory over Crystal Palace -- the club's first trophy in three seasons. Praising van Gaal for maintaining his dignity despite the circumstances, Koeman asserted that United does not deserve their FA Cup triumph due to their treatment of the former Netherlands and Barcelona manager. "I have watched the process around Louis van Gaal and Jose Mourinho from a distance. For months we were all reading that Mourinho was busy with Manchester United. If Louis was not told about getting the sack until after the FA Cup final, then Manchester United as a club don't deserve a medal for the way they treated him," Koeman wrote in his column for De Telegraaf. "If you know a little bit about the business at the highest level in football, then you know that these kind of deals are not done overnight. But Louis has been put under tremendous pressure for months. This is why I admire the way he kept his dignity," he added. "Of course, he had a number of run-ins with the media and there were moments when I thought 'Louis, you could have dealt with that in another way.' But Louis is Louis. Looking at the incredible pressure all around him, I think he did a great job winning a big trophy like the FA Cup." Koeman, who is currently the manager of EPL outfit Southampton, asserted that the arrival of Pep Guardiola as Manchester City manager, the return of Jose Mourinho to England -- this time at the helm of Manchester United -- and the unprecendented success of Leicester City means that next season's EPL campaign will be an exciting one. "The best managers in the world have now come to the Premier League. With Guardiola starting his work at (Manchester) City, with Leicester inspiring so many other clubs that winning the league is possible, and every club financially strong enough to buy top-class players, the Premier League will prove that it is the most fascinating competition on the globe," the former Barcelona star said. "The fact that guys like Mourinho and Guardiola want to work nowhere else makes it all more beautiful. This is the reason why I think it is fantastic to be part of English football. I find the intensity and the fact that the Premier League is totally unpredictable now amazing." Koeman expects Leicester's success to serve as a wake-up call for sides like Manchester United, Manchester City and Chelsea who performed below the expected standard during the 2015-16 season. "Leicester have made the impossible possible and that is the biggest of wake up calls for the big clubs. They will all need to react -- and we all know their budgets are almost unlimited. With Southampton, we beat every big club this season at least once," the 53-year-old said. "We only finished only three points behind Man City and Man United and we finished 13 points ahead of Chelsea. So we performed above the maximum of what people thought was possible. It is only going to be more exciting and competitive. Next season will be the most spectacular fans have ever witnessed," he added.