Sevilla won the Europa League this season and they were lucky enough to win this title but on the other hand, Sevilla have taken the final automatic place for the next champions league and they should get themself ready for the champions league where they are going to have harder games than what they had in Europa League. Sevilla couldn't have a good performance in most of the games in the Europa League and in La Liga but they should start hiring better players if they want to achieve something in the champions league.
It's not about being lucky, but Sevilla played well this season in the Europa League, and I have no doubt that they will prepare for the upcoming Champions League, even though I know the games they play there will be difficult matches in which they will face bigger teams than they did in the Europa League this season. I will be hoping to see them succeed when the upcoming Champions League season arrives.
Although there are a few positions in Sevilla's squad that require intelligent players, I agree that they should begin planning for the acquisition of new players to fill those roles in order to strengthen their team when the time comes to compete in the Champions League the following season. If they don't do that immediately and begin training the players to become acquainted with one another and understand how they play their games before the time, it will be difficult for them as well, so I believe Sevilla should do this.