It is not uncommon in history for teams like Sevilla FC and West Ham to fight for relegation at home and reach the final four in Europe. Bayern won the Champions League in 1974/75 in 10th place in the Bundesliga, and in 1981/82 Aston Villa won the Champions League trophy in the league ranking as low as 11th. 1983/84 UEFA Cup winners Tottenham Hotspur finished 8th in the league, 1979/80 UEFA Cup winners Eintracht Frankfurt were 9th in the Bundesliga, and 1996/97 UEFA Cup winners Schalke 04 were ranked even lower to 12th in the league.
As for the five major league teams with better results in Europe, more are struggling in the league. Bundesliga fans should not forget: Klopp's Borussia Dortmund were still in the relegation zone when they faced Juventus in the 1/8 final of the 2014/15 Champions League! Fortunately, after the Champions League exit, it rebounded in time and finally finished 7th.
Inter in the 1993/94 season still held the record of the lowest league ranking (13th) of European champions league teams. Inter signed Bergkamp and Juncker, plus Pantsev, Shalimov, Ruben Sousa and Skirac, but did not expect to be forced to change coaches all the way outside the top 4. Fire coach Marini gave up the league, 2 wins, 1 draw, 8 defeats and 4 consecutive defeats in 11 Serie A, dropping from 6th to 13th when he took over, only 1 point above the relegation zone, but in exchange for 3 consecutive wins in the semifinals and finals of the UEFA Cup to finally win the cup. However, Inter had good luck that year, and their semi-final and final opponents were Cagliari and Austria's Salzburg respectively.
In the 2004/05 season, Parma, who had just experienced a financial crisis and sold a large number of main players, had been fighting hard for relegation, and changed managers until the last round to confirm relegation. The UEFA Cup is almost "perfunctory" with young players, but after beating the stars and Besiktas at home in the group stage, he beat Stuttgart, Sevilla and Austria all the way to the final four, which is the fourth best European result in the team's history. Parma relied on the defense led by Cannavaro and Bonella, kept six clean sheets in eight knockout matches, and gave rookie Gilardino plenty of opportunities to exercise.
In the 2005/06 season, Middlesbrough played in the UEFA Cup for the second consecutive season under McLaren. At that time, the team had Hasselbaink, Viduka, Mendieta, Parol and other famous players, the team started from the league cup preliminaries, once unbeaten in seven European games and conceded only one goal, but the league was obviously affected by the lack of bench depth. After a 4-0 home defeat to Villa in early 2006, Myburgh was 17th at one point, a step away from the relegation zone. Miburgh has always been between qualifying for the UEFA Cup and relegation from the Premier League, relying more on luck. On the way to the final of the UEFA Cup, three consecutive away defeats are all thanks to three consecutive home wins. In the final, as a relegation team in the Premier League, the 4-0 defeat to Sevilla was a reflection of true strength. In the same period, the Premier League also alternated defeats and consecutive wins, and finally relied on most opponents who were weak in the second half and barely landed early.
La Liga teams occasionally have dark horses upset into the Champions League, the results are basically due to insufficient bench depth, European performance, the league is a mess, is the "civil war layman, outside war insider" hardest hit area. In the 2003/04 season, Real Sociedad finished runners-up in the league in 21 years and Celta reached the Champions League with the best fourth place in the club's history. But the bitter price paid by both teams was that the league had been struggling for relegation for the new season, with Real Sociedad narrowly relegated in 15th place and Celta relegated in 2nd from bottom to bottom. In the 2016/17 season, Celta reached the last four of the Europa League, but at the cost of a sharp decline in La Liga's form, with only 1 win, 1 draw, 8 defeats and 6 consecutive defeats in 10 rounds at the end of the season.
Another small team near the Basque Country, Osasuna, also participated in the Champions League in 2006/07 with the best ever La Liga 4th place, but the team was eliminated by Bundesliga powerhouse Hamburg in the third round of Champions League qualifiers, and "relegated" to the UEFA Cup also eliminated Bordeaux, Rangers and Bayer Leverkusen all the way to the final four, and defeated the eventual champions Sevilla in the semifinals. However, the team won only 1 of 12 games in La Liga due to European constraints, and scored a measly 7 points, and it was not until the UEFA Cup exit that they could concentrate on escaping relegation with 3 consecutive wins in the last 4 rounds.
Espanyol, a traditional mid-table team in La Liga, is no exception, and when they first reached the UEFA Cup final in 1987/88, the price was only 15th in the league, a far cry from third place in the previous season. The 2006/07 season was slightly better, also reaching the League Cup final, at least not suffering from the relegation crisis in La Liga, but only finishing 11th. Even Villarreal, who have always been consistent on both fronts, reached the last eight of the Europa League in 2018/19 while dropping to 14th in La Liga, the second worst since 2003/04 and behind relegation in 18th place in 2011/12. Getafe, who competed in the group stage of the Europa League in 2010/11, also barely relegated from 16th place in the league.