Indeed, Chelsea has considered this before facing the upcoming season, with the support of long-term transfers that can strengthen their team, so Chelsea has taken this into account in every decision they take to win the Premier League, because they are not satisfied with the 4th position in the Premier League last season by using new breakthroughs in their squad, it is hoped that their team will be more advanced.
Long contract doesn't make any team better but it's a strategy to make players want to do more especially when they have good season and want to do more for the club. They don't need to undergo any contract and it's more an advantage for club to keep players in the event if the player does more for the club, their market value will also be increasing, when the club is ready to sell them they can make more money from them, long contract has always been about money and not performance per say.
There players that went on loan to another club and has help the club win a trophy they won for long time. Some players that are loan has faced their parent club in a match and make sure they deal with them with goals. You can see it's not just about performance. Chelsea might do better but in bot faze with this hype we are getting. They did well in the finish club world cup but that's not the end, we will see each what they are going to do this season.