When La Liga clubs make a marquee signing, it is expected from that player to be one of their best players on the pitch and provide a competitive edge over its rivals.Sometimes such big-money signings end up disappointing in their debut season. A new club, new management style and troubles adjusting with teammates being just a few of the factors responsible for the same.Well, such disastrous signings are becoming the norm rather than the exception across European football nowadays, with clubs conducting their transfers the same way a toddler goes through his toys collection, moving on to the next thing if they don't like the first option.The recently concluded La Liga campaign too has seen a few very big signings struggle in their debut season for their new clubs. Without much ado, let us take a look at:5 signings who have failed to impress in La Liga this season:#5 Jasper Cillessen (Valencia)Cillessen's move from Barcelona didn't pan out as expected.We kick off our list with a former Barcelona goalkeeper whose disappointing performances made Valencia, who paid €35 million for his services last summer, drop him to the bench in the final games of the La Liga season.Jasper Cillessen was the first-choice goalkeeper for The Netherlands in the 2014 World Cup, where they finished third and it seems that was the high point of his career as everything has been downhill for the former Ajax star since then.This season in La Liga, he made 24 appearances for Los Che shipping in 30 goals and only managing five clean sheets. At a time when goalkeepers are known for their passing abilities, at 56.8% pass success, his distribution was poor and he looked unsure between the sticks leading to errors like the terrible clearance at Camp Nou in September which allowed Gerard Pique to score an easy goal.#4 Rony Lopes (Sevilla)Rony Lopes failed to leave an impact in Sevilla's impressive season.Sevilla finished fourth in the La Liga this season after an impressive campaign, with a few of its players making it into the team of the season, sadly, their summer signing from Monaco, Rony Lopes wasn't one of them.In 12 appearances across all competitions, he only bagged an assist, while Wissam Ben Yedder, the player Los Palanganas sent to Monaco in exchange for Lopes, ended up with 18 goals in the Ligue 1.🎁🎮 On a packé un nouveau joueur ! ⚽🔴⚫#Nissa21 #Fut #CarréCroix #OGCNice pic.twitter.com/7VAd8MMS1t— OGC Nice (@ogcnice) July 29, 2020He has not lived up to his exploits from the 2017-18 season at Monaco and after a hugely disappointing stint at The Ramon Sanchez-Pizjuan Stadium, he has been sent back to the Ligue 1 on a season-long loan with OGC Nice.At €25 million the Portuguese attacker was the most expensive signing in Sevilla's history and as the 2019-20 season proved, also one of the most disappointing. Also See: 5 best left-backs in La Liga this season (2019-20)