As the end of another Premier League season arrives this weekend, soon enough the transfer window will open and the money will start to flow. Every year, billions of pounds are sunk into deals that don’t work and deals that never looked like working to begin with. Footballers are not machines and any number of reasons can kill the chances of a transfer’s success. In the modern game, with the ever-growing mountain of information and data, clubs should be using any and every possible edge they can find to make sure they minimize their exposure to risks. Of course, not everyone does that. So, here are the nine deals from the past year that Premier League teams probably wish they could have back

Ross Barkley, £15m, Everton to Chelsea

It might seem cruel to put Barkley on a list of bad transfers as he’s barely had a chance to show what he can do for Chelsea after his January switch. One Premier League start, in which he lasted 54 minutes in a surprise 3-0 defeat at home to Bournemouth, and two substitute appearances in cup games make up the sum total of his game time for his new team. That might seem like bad luck, but the issue wasn’t hard to see: A mid-August hamstring injury meant that he played a total of zero minutes for Everton this season before his move.

With his last competitive game for Everton in mid-May 2017, Barkley hadn’t kicked a ball in anger in over eight months by the time he took the field for Chelsea. Just look at the savage looking scar on the back of his leg; this was no minor knock. Even if you concede that he must have proved some level of fitness to Chelsea in order pass a medical, a further hamstring problem has meant Barkley missed all of February and March and is only now being slowly integrated back into the squad, with the season all but over.

And that’s before getting into the other question: Is he even good enough for a club that won the Premier League just last season? Barkley’s career remains a tale of unrealized potential, while Chelsea used to buy exclusively from the top table, as even their discarded players now vie for Player of the Year awards. He could still come good, but with his Everton contract expiring at the end of this season, Chelsea could have saved themselves a good chunk of change, waited for the player to prove his fitness, and landed him in the summer. Instead, they now own a player who has barely played for a year, and hasn’t proved his fitness. Why didn’t they wait?

Davy Klaassen, £24m, Ajax to Everton

Everton’s profligacy during the summer of 2017 belied any clear plan. It was apparently driven by emotion (Wayne Rooney came back to his boyhood club), the manager (Ronald Koeman, who was fired before November) and bravado (£45 million for Gylfi Sigurdsson isn’t far off what Liverpool played for Mohamed Salah). If this column had a team award, they would be prime contenders. By the time the transfer window had shut at the start of September, Everton had spent around £140 million in transfer fees for new players.

Perhaps it’s unfair to pick out Klaassen from their list of new players, but his signing—which felt so obviously driven by his manager and countryman Koeman—embodied the lack of foresight almost completely. In signing Klaassen then Rooney then Sigurdsson, Everton found themselves with a surfeit of somewhat-slow, creative-type attacking midfielders. They also bought Sandro Ramírez from Málaga as a kind of in-between forward/attacking midfielder after he ran hot, scoring double his expected-goals rate with an unlikely-to-repeat 14 goals in 2016-17.

As a result, the strikers that replaced the Manchester United–bound Romelu Lukaku were 20-year-old academy graduate Dominic Calvert-Lewin and Oumar Niasse, who hadn’t even been given a squad number or a locker during the previous season before being farmed out on loan to the eventually relegated Hull.

To shoehorn two attacking midfield types into the side was tricky enough, but three or even four was too much. Klaassen found occasional playing time in an unwanted and failing Europa League campaign, and has made just three Premier League starts, not once completing a full 90 minutes. Since December 7, he made just two substitute appearances in a grand total of 16 minutes play. New manager Sam Allardyce appeared to see no future for Klaassen at the club and raged publicly when a deal to take the player to Napoli collapsed in the January transfer window. Klaassen stayed, Ramírez went back to Spain in January, Rooney scored from the halfway line, and Sigurdsson’s form returned to earth in an entirely predictable manner.

All told, Everton spent a lot of money to build an imbalanced squad. Predictably, they struggled.

Fernando Llorente, £12m, Swansea to Tottenham

Tottenham chairman Daniel Levy is an infamously tough negotiator, so it’s interesting to ponder the circumstances that led Tottenham to spend a reported £12 million on the then-32-year-old veteran striker Llorente last August. Did Sigurdsson’s £45 million transfer from Swansea to Everton include a sell-on percentage for Tottenham? Or was Levy seduced by a long-term target to override a long-term club policy of not purchasing older players? After all, Llorente had been in his sights since at least the winter of 2011, a bygone era in which Tottenham fans routinely dreamed of a coveted, highly priced, big-name striker before having to rationalize that hope against the free transfer of a declining Louis Saha.

Regardless, Llorente arrived and duly slotted into the undesirable Harry Kane backup role from which, well … he hasn’t really delivered. Five goals from 31 varied length appearances are made up from an FA Cup hat-trick against third-tier club Rochdale, a Champions League goal in a dead rubber match against Apoel Nicosia, and a solitary Premier League goal against his former club Swansea. As much as anything, his style simply doesn’t fit Tottenham. Mauricio Pochettino’s men aren’t a side that hits a big man like Llorente in the air with crosses, and often when he’s been tasked with coming off the bench and finding a late goal, he’s found himself barely involved in the team’s play. Apparently popular within the squad, his role has appeared almost talismanic: a former World Cup winner there to add experience and wisdom to a young squad. That’s fine in itself, but the fee—a world record for a 32-year-old—was undeniably expensive and the returns have been thin.

Kevin Wimmer, £17m, Tottenham to Stoke

Guido Carrillo, £19m, Monaco to Southampton

A joined-up process between whoever buys the players and whoever runs the team is essential for best practices within football. Sadly, all too frequently managers, who often oversee purchases, lose their jobs, and that has an impact on the playing staff. This season, twelve Premier League clubs sacked their managers, and West Brom did it twice.

Wimmer cost Stoke £18 million last summer, and during the first half of the season, he featured regularly in manager Mark Hughes’s new three-man defense. It didn’t work: Stoke conceded 40 goals in the first 19 games, five more than any other team, and found themselves in a relegation battle. Hughes was fired soon after. New manager Paul Lambert was appointed on January 15—that date was the last time Wimmer was sighted in a Stoke shirt. Wimmer was told he was “not the type of player” his manager was looking for, and that was that. Stoke were relegated anyway—with a player they made a huge investment in both alienated and unsighted for half the year.

Carrillo found himself in a similar situation after moving to Southampton. He arrived in January from Monaco for around £19 million, presumably with the consent of then-manager and fellow Argentine Mauricio Pellegrino. In five starts and one substitute appearance under Pellegrino, he didn’t score. Then Pellegrino was fired and Mark Hughes took the Southampton job, gave Carrillo seven minutes while 3-0 down against West Ham, and hasn’t played him since.

Managers evidently have different ideas about player quality. But these two deals go beyond that. Both players had featured only sporadically for their former clubs before their big-money transfers. Essentially Stoke and Southampton spent the best part of £20 million apiece on reserve players. Wimmer made just 13 league starts in two years at Tottenham while Carrillo had made 22 league starts in three years at Monaco. Neither had shown a great capacity for consistency or quality since before arriving at their former clubs. (Indeed, it has been reported that Wimmer has been on a special fitness program since Lambert took over.) Is it any wonder they didn’t hit the ground running when tasked with playing regularly for lesser teams? As of now, with Stoke relegated and Southampton at 22 percent to follow them, they just look like expensive mistakes.

Wilfried Bony, £12m, Man City to Swansea

André Ayew, £20m, West Ham to Swansea

“Never go back” is one of the oldest adages in football. The idea that past glories can be recovered rarely pans out as well as hoped and the natural trajectory of a player’s career backs it up. Players often leave a club after good form to improve their standing and earn a better contract at a bigger team. If they return to a previous club, it’s because their career is on the decline.

In Bony, Swansea went further still: They acquired a player whose status never rose above the level he had at Swansea two and half years prior and for whom the intervening period had become progressively less successful. In his first half season at Manchester City, he was mainly a substitute option, with the ever-present Sergio Agüero leading the way. By his second season, he managed 13 starts but eventually dropped behind Kelechi Iheanacho in the pecking order as the young Nigerian started to score regularly. Unwanted ahead of Pep Guardiola’s debut 2016-17 season, a dismal loan to Stoke saw just nine starts and two goals, and then-manager Hughes omitted him from the club’s squad from February onwards for reasons unknown.

This season has gone no better after a return to Wales: just two goals in 15 Premier League appearances, with his last start coming before Christmas. He’d already fallen down the pecking order and spent time out of the matchday squad before a cruciate ligament injury curtailed his season entirely in early February.

Amazingly, Bony isn’t the only Swansea player to have joined back up this season to diminished effect. Ayew returned from West Ham in the January window to add goal power, but he has yet to score in nearly 705 league minutes. What makes this deal more frustrating from the outside is that Swansea made the perfect play with Ayew in the first place. They signed him on a free ahead of the 2015-16 season, then enjoyed the best of him—aged 26 and 12 league goals—before selling him on for a high price. Perfect! Now he’s back and they’ve signed on to pay him for another three years, until well past his 31st birthday. If, as appears possible, his form is already in decline, the back end of that deal is going to look very expensive.

Add in an expensive loan for Bayern Munich’s Renato Sanches, who will be chiefly remembered for attempting a pass to the advertising hoarding. Then £12 million signing Roque Mesa, who promised his wife he wouldn’t shave his mustache until a Spanish national team call-up, yet by midseason, he still had the facial hair and was already back in his homeland on loan at Seville. With the margins so tight at the bottom of the table, maybe Swansea wouldn’t be in the relegation zone if they hadn’t tried to relive the past.

Joe Hart, loan, Man City to West Ham

Back in the summer of 2017, West Ham had a good keeper: Adrián. Throughout his time at the club, he had consistently saved more goals than expected. By way of contrast, England international Joe Hart had not, and was coming off a particularly chastening and error-strewn loan spell at Torino. Of course, West Ham signed him on loan for the season, anyway.

They’ve shared duties this season, with Hart finding favor early on before David Moyes started selecting Adrián again. Hart’s form has not improved:

Someone asked me to do one of those charts for a "shit keeper". In things that are unrelated here is a chart for Joe Hart pic.twitter.com/LHimvAz4wP — Colin Trainor (@colintrainor) May 6, 2018

Predicting Hart’s struggles was straightforward. A simple conversation with a Torino fan would have offered concern about Hart’s reliability, and 10 minutes with a stats guy would have resulted in a thumbs up for Adrián. West Ham spent much of this season battling relegation. Had they just gone with their better keeper from day one and not bothered to sign what they thought was a prestige “name” guy, that problem might have been resolved a lot quicker.

Adrien Silva, £22m, Sporting CP to Leicester

This deal looked tricky to square from the get-go: Silva was 28 years old and apart from a short loan at Israeli team Maccabi Haifa in 2010 had spent his entire senior career in Portugal, with the vast majority for Sporting CP. Although a Portuguese international, he was untested in bigger leagues, and with a four-year deal on the table, Leicester were lining up to spend £22 million on a player whose physical peak was perhaps behind him.

Then: The deal didn’t even get done. Leicester contrived to miss the summer-window deadline by a reported 14 seconds, so they were technically his owners, they just had no right to play him until they could register the transfer when the window reopened in January. So four months after originally signing, Silva finally saw some pitch time—and since then, it hasn’t gone too well: seven Premier League starts, zero victories. It’s never straightforward to attribute blame for results like that, but this deal hasn’t shown any upside whatsoever so far, and it remains to be seen if it ever does.